If it were me, I would try to find an integrative/functional pediatrician. There aren't many, but these types of doctors look at the whole person, rather than individual symptoms and diseases. Much less likely to prescribe medicine right away. S/he can test you and him for both gluten sensitivity and celiac disease (which should be done before eliminating wheat and gluten).
You are right to consider that food sensitivities might be causing or contributing to the situation. The two biggest offenders are wheat/gluten and dairy, so if you're using milk based formula, then it could be a problem. Soy based formulas can cause problems for some too. And you stopped breastfeeding, but if you went back to that for a while, you'd have to stop eating the suspected allergen as well.
If you've never dealt with food allergies before, it's not easy to just jump in and remove gluten or dairy without a lot of research first. The two foods are in many processed foods and even personal care products. For some, traces can cause a problem, and gluten especially is found in many things, and is not always labeled. So, I would not just attempt to do an elimination diet on your own without some guidance.
Another approach, after being tested for celiac, and gluten sensitivity (which doesn't always show up on lab tests, by the way, but you and your child should still be tested before doing a trial elimination), is to eliminate the top food allergens for 30 days and add them back, one at a time. If you or your child have a reaction when you add individual allergens back, then you are sensitive to them. Keep in mind that the reaction may take up to 72 hours to show up, so again, it helps to have a professional guiding you, especially since your child may have medical issues that food alone can't resolve.
After you find an integrative/.functional pediatrician, you might want to consider going on the Paleo (minimal allergens - real, pure food) for at least 30 days. You can find more information about this at Chris Kresser's site. He has a Healthy Baby code program that might be perfect for you.
So, to sum up, I recommend:
- Finding an integrative/functional medical doctor who is open to exploring dietary changes and food sensitivities (I also have a fantastic nutritionist (PhD) in NYC who has celiac disease himself and who I'd highly recommend).
- Get tested for celiac and gluten sensitivity, but making sure the doctor understands the benefits, limitations, and different types of gluten sensitivity testing.
- With the guidance of a health care professional you trust (hard to find, but they are out there), get tested for food sensitivities and/or do a temporary elimination diet. Consider a 30 day trial of Paleo, with guidance.
- Always do your own research and trust your gut. You know yourself, and your baby, better than anyone else!
It sounds like a lot, I know, but healing takes time and effort, and a lot of connecting of dots. You have to move beyond any one-size-fits-all approach. I know all this because my daughter has severe food allergies and intolerances, which led to the development of a serious digestive illness. By connecting the dots of a variety of specialists, healing foods, cutting edge nutritional philosophies, and sophisticated lab tests (beyond what conventional medicine can offer), she now looks and feels better than ever before. Each of us is different, though.
And again, you and your baby should both be tested, and make the changes together. Just keep in mind that no transformation ever comes without some kind of struggle! You've heard the wake up call, and it sounds like you're ready to take action.
Even if you ignore all this advice, if would benefit everyone in your whole family if you transition away from processed foods (even refined flours and pasteurized dairy products are processed foods). Think outside of the box, bag, and can. Shop in the outer aisles of your grocery store, or better yet, at your local farmers market. Fresh, farm-to-table food is best.
Good luck! The journey is well worth the time and effort.
I second all those recommendations. I've done a lot of research about gluten & celiac and all those symptoms could be eliminated if gluten is the problem. There are tons of great GF substitutes these days. Let me know if you need help tracking them down.