What Causes Weakness And Inflammation In Shoulder, Wrist And Arm?

I am a hair technician and I trapped a nerve C7 whilst training in the gym effecting the left side 18mths ago. It was quite bad and I couldn t lift my arm at the worst point as it was misdiagnosed. I had steroid injection, Physio, osteopath(who tore my shoulder muscle) it was an ongoing drama, and I decided to leave it alone. I recently Started training again. Did shoulder presses with 10kg each arm nerve has flared up with weakness to arm, burning in side of face, shoulder, wrist, arm. Training is important to my lifestyle and I would like to continue training do you have any advice as it is very frustrating and delibitating and I can t afford for it to get worse due to my work. Could you please advise on supplements and therapies that will assist me.