WOW! That is a MASSIVE dose. The usual recommended single dosage per day is only 0.2 mg /kg, which for me (85kg) is only 17mg.
It probably is nervous damage. You nerves normally can recover though. I had some nervous problems after taking lots of Metronidazole, so have some experience here. Get off the drugs immediately and let your body recover. Get on vitamin B complex supplements, as these are known to be necessary for nerve repair, and start eating more Vitamin B-rich foods such as eggs.