I had an allergic reaction to Metronizadole and was initially accused by a doctor of drinking alcohol, which I wasn't.
Despite my allergy being noted on my hospital notes, (as well as other medication allergies ) I was given it again in theatre in a drip , under it's other name Flagyl.
I had a spinal block and could hear everything that was going on, that's how I knew. I tried to tell them, but it was too late.
I had to spend an extra week in hospital, as result!
However, it is very effective in combating mouth infections and reading the articles on it, allergic reactions seem to quite infrequent. I just happen to have a history of multiple allergies.
I hope you get some relief soon.