Hello, Thank you for your query. Your symptoms indicate weakness in the muscle, probably due to nerve damage. Would you clarify a few things for me? *what is your height and weight? *do you smoke or consume alcohol? *do you have any other medical issues or take any medications? *do you use your arms, shoulders a lot (like a computer)? *are you mostly sedentary? *any Injuries to you back or neck? I recommend : - a neurologist consult right away. -x-rays of the cervical and thoracic spine and an MRI to detect nerve compression. -an nerve Conduction study if indicated (based on clinical findings) -blood tests (complete blood count, liver and kidney function tests). Please see a doctor right away for a prompt diagnosis and treatment. Keep moving the muscle as exercises thrice a day. This is to prevent muscle wasting when bit being able to use it. Use you other hand to passively flex and extend muscle that you have trouble with. Do this several times a day. Based on the clinical findings and test results a diagnosis will be made. Hope this helps. Please let me know if there is anything else I can do to help. Wish you good health