Hi Theworldisyours
Welcome to NeuroTalk

. I hope that you will find the community both knowledgeable and supportive.
I am sorry to read about your peripheral neuropathy.
PN is listed as a "rare" side-effect of Flagyl and its only reported interaction with a recreational drug is a "Major" one with alcohol.
The information here may help you with this.
Flagyl Uses, Dosage & Side Effects - Drugs.com
Best wishes.