You were on a medium sized dose of Gabapentin for seven weeks, but you were on high dose Valium and Ambien for 3.5 years beforehand. You don't think that's a contributing factor?
Post acute withdrawal symptoms from benzos and z-drugs (gabapentin is neither) can last a VERY long time. I also don't know how fast you tapered, but the faster the taper the more brutal the symptoms will be.
Yeah, it sucks, but that's GABA drugs for you. Gabapentin, by the way, is not a drug that acts on GABA in any way. I have been at 900mg/day for a while now. i can miss a day and feel fine. If I miss a few days, it feels like a slightly more intensified marijuana withdrawal - insomnia, loss of appetite, increased anxiety and irritability, etc. But these symptoms are NOTHING compared to hardcore brutal benzo detox. Cold turkeying 10mg Xanax per day was one of the most terrifying experiences of my life. I've also kicked intravenous opiate use too, had to taper using Suboxone, Both of these make Gabapentin withdrawal seem laughable.
I'm not discounting your experience, and obviously everybody's bodies are different. But I read all these "gabapentin withdrawal horror stories" and I can't help but wonder if the people writing them are either a) currently still dealing with a different withdrawal or PAWS, or b) kind of over-exaggerating the symptoms. Don't get me wrong, this stuff does have a withdrawal, but I find it extremely mild compared to opiates and benzos. Then again, the intensity of withdrawal (of any drug) will be directly related to the dose taken, and the amount of time the substance was taken for.
I'm sorry you're going through this and I'm sorry if the above post came off as assholeish. I guess my best advice is to slowly taper your gabapentin dose - as slow as you feel comfortable doing, until you're ready to hop off. That's generally the best way to get off any medication.