Oooh, goodness no, there are lots of meds and drugs and herbs and vitamins to try! I found a lot of pain reduction when I was taking Lamictil, which is officially an anti-epileptic I think, but has a very nice side effect/off-label use as a pain reliever for neuropathic pain. A bit along the Neurontin theory. It really kicked my FM pain down about 5 points! (naturally there were the usual neurological drug icky-but-tolerable side effects like dry mouth/eyes, wobbly hands). Now I'm taking Topamax instead, which is quite feeble compared to Lamictil's pain relieving strength, but it does dampens the pain down by a point or two (on the 10 point scale...).
Please don't give up. The fact that Neurontin was working for your pain is very encouraging, and I would think about trying a few more drugs in that class. There is a lot of new research showing that anti-epileptics are effective at tough pain like FM, so perhaps your doc could be persuaded to try 1 or 2.