I don't know if this is an allergy thing, per se, but it may be nutritional/supplemental.
DS was in a whiny phase for the past week or 2, and had meltdowns whenever he was told "no." (no matter how nicely it was put, or how re-directing we attempted to be) I thought maybe it was because we were coming off a week of family visiting, where we had less of a schedule, and he had lots of 1-on-1 with my sister (who is FABULOUS with him - she mainly works with children with autism, so "managing" DS was a breeze for her). I thought maybe his increased emotional fragility was related to her leaving, but it went on all week.
The weekend was particularly tough, although he had one-on-one almost all weekend, with either myself, DH, or both of us. He had tons of fun at an indoor playground. But, man, I was glad to get him back to daycare Monday morning.
Monday I also started him on Focus Factor for Kids, and making sure he had his Nordic Natural's DHA CLO daily. My decision to start him on a vitamin stemmed from the fact that he stopped nursing last week (yes, in the middle of the whiny week). My decision to use Focus Factor was based on the fact that it was the ONLY one available locally that didn't have any artificial flavor or color or any of his allergens. Here is a link to the ingredients - http://www.factornutrition.com/index.php/product-family/focusfactor-for-kids#
A link to the Nordic Natural's he's been taking - http://www.vitasprings.com/children-s-dha-liquid-8-oz-nordic-naturals.html
Prior to this, he was probably getting 1/2 tsp CLO 3-4 times a week.
He's been a breeze all week. No melt downs, no whining. When he is told no or is disappointed ("We're going home for dinner. We're not going to the gym today."), he frowns and sometimes makes a whimpering puppy sound. That lasts less than 10 seconds, usually less than 5.
I have NO idea if it is a coincidence. I wouldn't say that he has more focus, but man, he is back to his happy self, and *I* am happy about it.