Hang in there and keep reading as much as you can about anatomy - nerves, blood, muscles- and symptoms relating, and you might find what might be at the root of what happened to you.

I know it is tough to not get down in the dumps
- but it seems to me that something must have got torn or overstretched and it just might heal in time if nothing messes it up and no complications set in.

The nerves tell the body how to respond so maybe it is the nerves partially affecting the blood/color do the arm also...

I don't know how deeply the drs have looked into all of that for you....