Sulfa drug allergy timeframe?

Hello: I was diagnosed with a UTI and given sulfa drugs. I had some reactions but kept taking the drug. My doctor then put me on a medrol dosepak of steroids to fight the allergic reaction. Fine. Two weeks after finishing that, my face swelled up again. Back on another dosepak. Fine again. Again, two weeks after that, I now have sharp stomach pains and just the other night, my face swelled again. Can this still be the reaction to the sulfa drugs? Or is it possible that I am now hypersensitive and having reactions to other triggers? I am scheduled for an upper GI for the stomach pain but that's over a month away, and the only stomach relief I get is when I take Benadryl. Thanks for the help--Beth