Hi, I had gone through your question and understand your concerns. Your symptoms are probably caused by neurological condition that needs further investigation. This is the cause of neuropathy or damage to peripheral nerves together with muscles. There are some neurological and non neurological diseases that may cause neuropathy, some of them serious conditions. I can mention Diabetes neuropathy, Guilliain- Barre syndrome, Multiple sclerosis, toxic side effects of medications etc. If your blood work for Diabetes, and MRI ( brain) showed no problems, then Multiple sclerosis and Diabetes are very unlikely causing your symptoms. However I suggest you to consult a Neurologist and discuss your concerns. Hope this helps. If you have further questions feel free to ask.