Symptoms in the arm and leg would usually localize to the cervical spinal cord or above. You seem to have had a brian MRI but not a cervical spinal cord MRI? this might be worth pursuing
If you are sleeping with your elbows pressing down on the bed, you could be pinching the ulnar nerve at the elbow on one or both sides - this could result in numbness in the 4th and 5th fingers on waking. If minor, the EMG could be within normal limits. If pinched nerves like carpal tunnel syndrome have been ruled, it may be that your problem is not neurological
The increased sensation in the foot could be a neuropathy of which diabetes or 'impaired glucose tolerance' (early diabetes) is a common cause - you might want to get checked out for this also
Otherwise I cannot give you any more insight or a clinical diagnosis over the internet
All those symptoms could have a neurological origin, especially if they all arose around the same time. The possibility of immunological involvement should be minimal in the absence of an obvious infection/exposure. There may be an immunological basis to this in terms of autoimmunity, but were that the case, stimulation of the immune system would not be adviseable.
Sorry to hear about your situation. The fact you say it appears stable is positive and suggests the likelihood of reversibility and recovery once the underlying cause has been found. If I were you I'd demand thorough investigation to establish a diagnosis. Everything has a cause.
Have you been checked for Mono? The itchy skin is suspicious.
If I were you, I'd get in the nearest dry far infrared sauna and start doing this daily for 30 nminutes and drinking lots of water. This will help your body activate your immune system and clear out invaders and then eliminate them and toxins throught sweating, urine and feces. It's just and thought and what I'd do. Your arm pits are sweaty and damp and that tells me that you need to detox your body. As always, it is imperative that I recommend you discuss all complaints and treatment options with your physician.