I have a Penicillin alertgy, so I
was prescribed Sulfa Methazone, or someting like that.
I reacted to it immediately. Badly.
So the Doc switched to ....escapes me.
Does it matter? Let Doc choose an anit-biotic.

Also took an anti-bacterial. I remember that name but hesitate to be specific.
There are many. All this followed a total gut purge to nothing, as preparation for the colonoscopy. I think the new drugs hitting a totally empty system was part of the deal.

Good luck. I'm at week 5 since and still so much better. Not 100% but approaching. I'm 75, after 4 years LC, so 100% normal is an unknown state to boot.