I've had fibro for the past 4 years and on my first year of being diagnosed, I was prescribed Gabapentin. I didn't see it helped me at all and on top of that the side effects were more than the remedy. But like everything, it could work for some and not for others. I just tried it anyways.
Gabapentin screwed me up big time, my digestion was so bad that it was almost as crippling as my injuries, however, to put it into context I was on 3600mg/day, so a hefty dose. I am now on pregablin which has changed my life, albeit having to reduce the gabapentin to zero over several weeks resulted in withdrawal sweats/shakes & bad head space.
I suppose what I want to say is that as long as you start on a small dose and slowly build up (if necessary) if you get any unpleasant side effects (foggy brain is almost a given though) I would get straight back onto your gp and ask to be put on pregablin instead, it's also a brain fogger but to be honest, sometimes that's not a bad thing....
Gabapentin isn't exactly a pain med, it's a nerve blocker. Meaning it blocks the pain signals from reaching your brain. I have been in Gabapentin for years now for nerve damage pain, my stepfather has been on it as well but for chemo related neuropathy, and my husband was on it briefly for back pain. It's worked very well for us, and for me I am on a higher then recommended dose: 1200mg 3 times a day. I will say, withdrawal from it is a bitch.