you need to go to a physio.. anyone would know that especially a doctor.
change ur doc, cos obviously they don't know squat.
i tore the muscles off the left side of my spine when i had my hand kicked by one of my horses last year..
it takes two years for nerve damage to start to repair, and if you can still move your fingers, you will get the rest back.
stop trying to make it work when it needs total rest and time to heal properly, you are only doing more damage. i learnt this the hard way and suffer for it daily.
completely stop trying to make the muscles 'work'
use gentle exercises to slowly build the muscle back up over a period of months.
if the injury is new, then stop and see a physio immediately, if its old.. then your doc should have sent you to physio immediately and should know better.