Something else to consider might be adding some probiotics to your LO's diet fo at least a few days to see if it makes a differerence. Some babies have a hard time digesting things if they've ever had antibiotics in their systems; this includes the antibiotic IV moms get if they're Group B Strep positive! The first few days of her life, Natallie would fart so much and the smell could clear a room, but after I gave her some probiotics (I think she was 5 days old), that stopped and she's been fine since then.
I would NOT go back to wheat and hope he'll grow out of it; wheat's a pretty common allergen, and no, they DON'T always "grow out of it." (Ask my friend who's been told that while her DD may grow out of her egg and dairy allergies, her nut allergy is very likely lifelong.
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Definitely check out chiropractic; it's worked miracles for some babies. Avoiding the common allergens should also help - wheat, dairy, eggs, nuts, and soy, although it sounds like soy might be OK for you (fermented is better, like tofu or miso, or so I'm led to believe through all my reading, as plain unfermented soy - any legumes - is starch AND protein, which don't alwys digest so well together and so can cause gassiness).
Good luck and keep us posted!