Did you quit it cold turkey?!

How long were you on it? Did you ask your doctor or the pharmacist for help with stopping it? It's one of those meds that you probably need to gradually lower the dosage for it if you were taking it a long time or at a high dose.

I took Lyrica (similar to neurontin) for two weeks and quit it cold turkey and the withdrawal really sucked. I also didnt ask for help quitting it. (couldnt break up the pills because they were capsules) Even for only taking Lyrica for two weeks, it was long enough that I had a heck of a withdrawal from it.

edited to add:

the half-life of neurontin is 5–7 hours. It should be out of your system in 2 days.