Have you been tested for small intestine bacterial overgrowth (SIBO)? That could certainly explain a lot of your symptoms. Mind, so could a Crohn's flare-up...
At any rate, if you suspect bacterial overgrowth, it's possible to be tested for it. Treatment usually involves a week's course of antibiotics. Diet-wise, your aim would be to starve out the bacteria by not giving them an excess of carbohydrates to feed off, so gluten and dairy-free would be a start but not go far enough. Couple of links:
http://www.gidoctor.net/diet-ibs-sibo.phphttp://www.siboinfo.com/Hope that helps...