Keep searching for answers. God Bless the people on the forums for sharing information. Sorry to hear you're having med problems on top of your pain. If you search for posts about Neurontin by Rockhound you'll find beau coup info. On this one Dr.
Weight gain no problem.
You might want to check this out with your pharmacist. Seems they can cause seizure problems when taken at the same time. Both can cause drowsiness and weight gain. Sounds like it's just too much for you. I hope you can find a combination that will work.