A good start might be to post what you've been eating for the past few days. There are specific food allergies that might send up red flags for folks here who've had similar problems.

Considering that you've tried the very steroid I would have recommended as worth a try, I'm thinking that there's another trip to your doc gonna happen in the near future, and he/she will take the easy out by telling you that the only new thing in your life is your diet. (can't fault that...but it doesn't really get at the root of the problem, either!)