I take gabapentin for nerve pain. It took me a few weeks to get used to it. I would give it another week or so. If it's still making you feel that way after that, I'd suggest calling your doc to see if you should be feeling that way.

I barely notice I'm taking it anymore. Except when I forget to take a pill and within an hour or two - I am reminded by little shock like pains why I'm taking this.