I was on Flagyl for several months taking the same dosage you are. I didn't have any numbness or tingling effects, but I believe the concern is about nerve damage which can happen. That is probably why your dr cautioned you.
Even on weekends, drs are reachable through their answering service, so I would not hesitate to call and leave a message about your symptoms and ask for a call back. It doesn't mean I think anything is wrong (I'm no doctor!) but since your dr cautioned you, it seems reasonable to follow up. Since he told you to 'stop immediately', I'd definitely call, before taking any more as he said.
Flagyl is useful because it helps break up the cysts that Lyme bacteria hide inside, so then the amoxicillin can kill the bacteria, I believe. There are other options, so I have been told.
Let us know how it goes.
Welcome. I would let your doctor know about your symptoms and see how he or she feels about it. Antibiotics often need to be changed as the bacteria alter themselves and become resistant to the medication.