Well the food allergy thing its very complicated in some cases. Just do as Onwards suggests and rule out for a while the most common offenders. Personally im afraid I am intolerant to almost everything as my eczema shows but at least I stay away from soya,corn,wheat, gluten, dairy etc. If I eat fruit or cookies the effects of intestinal inflammation and IBS are greatly boosted. I cannot say about Depression or pain, every day something different pops out so its impsossible to discern but clearly eating more healthy makes me feel "less worse".