After doing some neck stretches, my left shoulder went completely numb. Why?

Hi doctor,

I have had some symptoms for the past six years. I feel like to have some pressure or imbalance on the upper left side of my body. Sometimes, I have brain fog. Sometimes, my upper rib seems to be tight while inhaling. Sometimes, I have dizziness and my heart rate gets raised. I did some tests recently. The doctor told me that I have an inflamed supraspinatus tendon. I am doing exercise and stretches every day. But it did not help me. I have tried palpating my tendon and there is no tenderness. Recently, I have tried doing some neck stretches. On the next day, my left shoulder became completely numb. Before having these symptoms, I had an incident in my gym on a day when I was doing my exercise hardly. After that, my vision became dark and I got constant pain in my shoulder or neck for a few weeks.