I had an extreme anaphylactic shock reaction to macrobid, I think about 6 months ago, every since then I have had heightened skin reactions, can u tell me if it has something to do with the reaction possibly? At this time I have a reoccurring patch of hives on my chest, bout the size of half a hand, It comes and goes. I take lortidine, but it doesn't seem to have any affect on it, can Benadryl have any affect on it?