I am sorry I am too tired to read all the other responses but my first thought is that this is not really an allergy problem so much as a malabsorption problem. There is a quote from the Specific Carbohydrate Diet something to the effect of "whatever the person eats that they cannot digest causes them harm." It's not about an allergic reaction, it's about a food that cannot be properly broken down by your body, and so it lingers in the GI tract and feeds pathogens, and the pathogens (bacteria, etc) excrete toxins that irritate the GI tract. Or it could be allergies in addition. We dealt with blood in stool for over 2 years. I highly recommend the GAPS diet for amazing healing. It cuts out all grains. My daughter was on a whole foods, no sugar, GFCF, no top 8 allergens diet for a long time, and even then, she slowly started having more and more undigested grains in her stool. Grains are a problem, even GF grains.
I never noticed an issue with corn really but learned that it can cause leaky gut. In situations where you are niacin (it's one of the B vitamins anyway) deficient, the gut opens up to let part of the corn in because it can convert that part to niacin.
Strawberries can be very irritating to the gut and also problematic for people with overgrowth of bad bacteria in the small intestine (SIBO), which can result in mushy/whipped stools. Strawberries contain sorbitol (so do stone fruits) which the body cannot digest. Normally it just passes through, but when pathogens are present it can feed them.
I learned we had big problems digesting fructose. If this is true for you, then you might be able to eat bananas (fructose to glucose ratio of rear one to one allowing easier absorption of fructose) but not fruits like apples (frucotse to glucose ratio much higher). Strawberries are in the middle.
Ok, I'm just scrolling down and seeing some other things pop out. DD had reflux too. The regular GI specialists dont really understand this. This is a symptom of an underlying problem, likely that the liver is stressed out by having to rid an excess of toxins from pathogens in the gut.
The screaming is NOT behavioral. I really think it's indicative of pain.
Please get the GAPS book and keep an open mind. I wish I had done it sooner. It could have saved us so much suffering (health, my marriage, etc).