...how long until you see signs after they eat it? And how long did it take for you to see the change when you eliminated it from their diet?
I'm a long time lurker, and a few months ago I came across a thread about behavioral issues and dairy allergies. My son was EBF and had reflux until around 12 months that was somewhat controlled with meds. Before putting him on meds at 4 months, I did eliminate dairy (including hidden dairy) for two weeks with little change in his spitting up (his BMs have usually been normal, no skin issues to speak off, nothing really that screams dairy allergy). Looking back, I know see that introducing cheese at around 8/9 months coincided with what I thought were early tantrums - he would scream, cry, kick, and alternate between pushing me away and being very clinging. I thought it was somewhat normal, he's in daycare for 10 hours a day, and thought he was stressed by that and missing me. He has also never, ever slept through the night - he is 2 years old now. Until I night-weaned him at 15 months he would insist on nursing all night long (we co-slept from 2 months until this point because I couldn't function waking up to comfort him every 45-90 min and he was easier to settle if I was right there; plus I learned how to sleep while he was latched on). Finally, I couldn't take it anymore, and night weaned him, hoping that it would help his sleeping (and mine!). After the initial rough phase, we settled into a waking between 3 times in a good night and 10+ times in a rough night. This slowly progressed into boughts of insomnia in the early morning (around 1-2am), in the beginning they lasted about 30 minutes and eventually would last from 1-3:30am or so; on the nights this didn't happen, he would wake between 3:30-4:30 and tell me he was 'all done' sleeping. I get up at 415am to get ready for work, so I felt like I was barely surviving! During this time, we bought him a full-sized bed, which helped a little (he hated his crib from day 1), moved into a room next door, black out curtains, strict bedtime routine, etc. etc. we tried everything to get this child to sleep (even letting him CIO for 15 min when he was around 14 months old because I felt I had tried EVERTHING at that point - just made things worse for weeks)!
His tantrums also continued to get worse and more 'extreme' - two months ago it was hitting his head against the floor/wall, hitting himself in the face, scratching his face, gagging himself, throwing things, hitting/kicking me, pulling hair, etc. anything could set him of. It was like he would go somewhere else - if he heard my voice or I touched him he would flail violently around. This would last 30+ min before I found that nursing would eventually calm him down (he would continue to cry and whimper 10 min in, but would eventually calm down and let me hold him). He would have meltdowns 5+ times a day, with 1-2 of them being this extreme; he would have them at daycare, but they tell me they never got quite this bad.
When I came across the thread about behavior and dairy, I eliminated dairy from his diet (main sources, not hidden) from Thursday evening until he went back to daycare on Monday. While he still had meltdowns, very rarely were they to the degree they were before, especially by Sunday afternoon, and while he was still waking at night, the insomnia was gone and it would take 10-20 min to get him settled (I also slept in his room with him occasionally so that we could both get sleep). By Wednesday/Thursday, the sleeping and behavioral issues were back and we would start all over again. I did this for 6 weeks until I felt pretty confident it was at least a possible contributor - luckily, our family doctor is wonderful and was willing to write whatever note we needed to allow for us to eliminate the dairy (only main sources, I didn't think about eliminating hidden dairy) while he was at daycare for a month to see if this was the issue. It's been 4.5 weeks, and while he still is 2 and has meltdowns and is still waking at night, it's not as extreme. We even got to the point where he would let us put him in bed, give him a kiss, and he would roll over and go to sleep - completely unheard of with him - and he was waking between 1-3 times, only requiring putting the covers back on him and a kiss; plus he was sleeping until 6am now. He hasn't hit his head against anything, hasn't tried to gag himself, and when he's having a tantrum, he hears me and I can usually find a distraction or he'll let me hold him until he calms down - they rarely last more than 5-10 min.
This could all be a coincidence - we hadn't tried helping him to learn to sleep on his own in awhile because we were just trying to survive (my husband works a lot of overtime/backshift and I'm 7 months pregnant with our second), so maybe he was just tired, leading to the dramatic mood swings, he was with me on the weekends, so less stress, etc. etc. We really tried to help him with the sleeping now because I am on 2 weeks leave from work and could nap if he had a rough night. And because it hasn't been a miracle cure (he didn't suddenly start sleeping through the night and he does still have meltdowns that involve hitting/kicking, etc.), I can't for sure say it's definitely the dairy. So, we decided, with the support of our doctor, to start giving him small servings of dairy. Our doctor suggested a little bit of cheese over the course of a few days and then try cottage cheese (I think she suggested that because those are the foods that we have had the hardest time replacing at his daycare), so I gave him a little bit of cheddar cheese for his morning snack yesterday. He fell asleep for his nap 30 minutes after having it, which was about an hour earlier than his normal nap time - unusual for him at home, but not unheard of - but no noticeable major tantrums or other odd behavior, except being pretty hyper in the evening and hard to settle to go to sleep at night. He woke up 3 times and required I hold his hand until he fell asleep and woke up 30 minutes earlier than he has for the last few weeks. Again, he hasn't needed this in a few weeks, but it's not unheard of.
I apologize for the length of this, but wasn't sure what info would be helpful. Thank you for any help!