You are experiencing side effects
of Neurontin, is all. Diff people react diff ways to it. Me, I have nausea that bothers me a lot. The weight gain you ask about is one of the side effects
, as are the other problems you are having. I've been taking it for two years, and I also started out on Lyrica, but becuz of cost I had to switch. Neurontin has only been around for about 15 years, so for at least for that length of time you're good.