Most of the pain meds have that sleepiness side effect unfortunately. He tried neurontin and although it works quite well for most people, that's why I mentioned it, it didn't for him even at high doses. 200 mg isn't that high of a dose really but if you already experienced pretty bad fatigue with it you might want to try something else.
There's another med called Lyrica, which is very similar to neurontin, but has a lot fewer side effects. Some others ones hes tried are Elavil, Tegretol, and Dilantin. I'm sure I'm forgetting some, his neuro went crazy there for a while trying to find something that would work and ended up sending him to pain management for the next step. For majority of people though, with trial and error usually they can find something to give you relief. Don't give up the search, keep trying something til you find one that works for you.
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