I am 42. About a decade ago I went for an MRI of my neck because of constant, intermittently-cripplingly painful, pins and needles all down my left arm. The MRI showing some bulging and malfooglelations in the cervical section of my neck. Nothing "too serious" and nothing than cannot be fixed without an operation. A procedure which I declined. I stopped all impact sports: Weights and basketball and eventually it went away. I was delighted. But a few months ago I noticed a grim loss of muscle mass only on the left side. I still carry on the very basic of activities like push-ups, sit-ups, and basic DIY around the house, running up stairs instead of taking the lift, etc. The worst affected are my triceps, then my peck, then deltoid, trapezius. My left bicep, appears, surprisingly, much less effected. Now noticing that the itchy skin on my quadrecepts has led to a tiny muscle loss in my left leg too. The GP sent me for another MRI which showed similar issues, minute dislocations and inter-spondelae constrictions on both sides. Nothing "too serious". Then I took off my t-shirt and showed him, advised him of all of the above and provided additional info like history and muscle twitches, and cramps whenever I try to tense under load or not, of said muscles. He said: "No F-ing clue! Referring you to a neurologist, but don't hold your breath!". Can some kind of specialist provide me an initial, basic diagnosis, please, as you understand I am very worried.