The normal EMG is somewhat reassuring that it's unlikely to be ALS if done at a reputable facility by a well-trained physician, especially if that leg is symptomatic. However, this needs to be taken into clinical correlation with your symptoms and neurological examination. Also, the EMG exam for ALS is quite extensive and includes one arm, one leg and different muscles along your spine to be complete. The major blood work should consist of muscle enzyme proteins such as CK and aldolase, as well as routine electrolyte studies. Depending on what they find with your exam, an MRI of the spine may also be a consideration. In addition to or in lieu of seeing the rehab doc, you may consider a second opinion by another neurologist with a subspecialty in neuromuscular diseases. Finally, a more invasive and sometimes more definitive test would be a muscle biopsy, again depending on what your doctors find. Good luck.
As a follow-up to the above I do not notice a change in the way my legs / arm look (atrophy?) and I am not experiencing tripping, falling, foot drop or inability to button, or do similiar tasks. Hope the dr. can read this bit as well.
I am not a doctor, but I have been researching neuro issues for quite a while and I think it is highly unlikley you have ALS. ALS is characterized by progressive weakness - parasthesias - the feet falling asleep are not a hallmark of ALS. Any number of far more benign conditions can casue you symptoms. I am sure Dr. JT can shed some more light on what might be causing your condition.
Ian