If you really believe it's tied to food there is only on way to know for sure. I would do the master cleanse. Now this isn't for everyone, and if you are only 98 pounds, then you might only want to do it for 10 days. When you are clean, then you can easily introduce one food at a time. If you still have the ringing towards the end of the 10 days, then you most likely don't have a food allergy .
I mean, that seems logical to me? But I hesitate to even suggest it, given your weight. Perhaps you can go on the Master Cleanse Forum (if you don't already know about this) and ask them. There are some real experts there. I had amazing results in 6 days, but the ringing persisted throughout.