Welcome to the chronic pain forum. So sorry you have reason to be here, but this is a great support group, although we're not doctors.
I also take neurotin. I'm now taking 400mg/ 4X/day but it took me a long time to work up to that dose. My neurologist originally started me on 300mg at night, and then wanted me to work up to 300mg/3X/day within a week! Well, I had to go much more slowly. I finally - after practically begging him - got him to give me some 100mg tablets, and I inched my way up from there. Took me a year or so to get up to what I take now, but it does help the neuropathic symptoms in my feet.
I don't recall being nauseous. Just tired. And I remember at first I got some blurred vision for a few weeks, but that went away. But I definitely feel the neurontin dulls my alertness more than anything I take. If I had good insurance (right now I don't have any!) I'd try lyrica, as it's newer and is supposed to have fewer side effects.
The cymbalta was great when I tried it, but I had to stop because it affected my seizure threshold (I have a seizure disorder, also). That was the only side effect I had from that medication. At the 30mg level, it helped my depression, but at hte 60 mg /day it was the only medication that helped my feet to feel somewhat normal again, but that's exactly about the time it gave me the other problems. I'd definitely try it, and/or the lyrica, if the neurontin (I also take the generic, gabapentin) is giving you side effects.
You might try calling your pharmacist if you can't get your doctor today, and ask if this is normal. Either way, I'd call your doctor and maybe ask about one of the other meds.
Hope this helps a bit!