Long time (5 year) neurontin user here. I have CRPS in my foot as well.

The doctor is right that you are on a relatively low dosage. I take 600 mg three times a day (twice what you are taking) and I understand that some people take 3600 mg daily.

I would absolutely agree with increasing your dosage a bit to see if that helps. You need to titrate the amount of drug you take until you find the lowest EFFECTIVE dosage. That involves some experimentation both up and then back down again. Everybody is different. Some people do better with dosing 3 times a day; some four. I found that three is enough as long as I take 600 mg each time, but if your doctor asked you to try an additional dose, I'd start with that. It took me about a year to find the right dosing strategy.

As for side effects of neurontin, the main ones for me are dry mouth (which got better over time) and a bit of brain fog or forgetfullness. And oh yes, some occasional nausea, but nothing real debilitating.

As for the effects of neurontin wearing away eventually, I haven't found any evidence of that, either in print or in my own use and others that I know. So don't worry too much about that. I'd try to maximize the effectiveness of it as best you can. As for trying Lyrica, Cymbalta, etc. you would never know unless you try. It helps some but does nothing for others. I tried both and had no success. Neurontin is my primary med. for my CRPS. I also take naproxen sodium (over the counter) which helps a bit with swelling and pain; I also take amitriptyline which helps a bit with my CRPS and trazodone to help me sleep. Sleep is very, very important. Without a good nights sleep, it's tough to handle chronic pain.

And for exercising, you need to find your own personal threshold. For me, it's about 20 minutes on my feet and then it's time for a break. "Use, but don't over-use" is my mantra. Everyone is different here as well. Don't push too much; pushing through is not an effective CRPS strategy. It can set you back and start a pain flare.

Too much caffeine and alcohol are not a good thing with CRPS, but small to moderate amounts don't have any affect on my symptoms.

Good luck and be sure to keep us updated!