--sent you a PM--and I agree with Aussie you do have to distinguish between feelings of weakness and actual weakness, such as her quick testing may help you determine.

Small fiber neuropathy by definition will not cause weakness as it involves only sensory nerves that subsume pain and temperature sensations and some autonomic systems. But the feelings one can get can be so varied it may feel like weakness, so actual muscle testing may be called for. And, as you mention, sometimes syndromes that start out as small fiber will spread to larger fibers, including those that control motor functions; the process (whatever one) that affects the axons (nerve fibers) of the smaller nerves may also affect the larger ones.