You'd be surprised what sorts of things can be caused by food. Wheat can cause inflammation in people who aren't necessarily intolerant, and it can manifest in really odd places. A friend of mine gave up grain and within a couple weeks his asthma was vastly improved, and a ganglion cyst on his wrist was completely gone. Boyfriend gave up grain and six months later shaved over half an hour from his previous best marathon time (which, if you don't know much about running, is pretty major). When I gave it up, the puffiness under my eyes disappeared in a matter of days and I stopped burping so much.
It's not for everyone, but the people I know who have gone grain-free have only had positive results, even if it's just weight loss. Wheat is definitely the worst offender, but most people don't need all the carbs in grain anyway. I now believe that if you have any mysterious health issues, diet is one of the first places you should look for improvement.