Problem In Pitching Ball. Arm Shakes, Red, Swollen, Unable To Grip. Solution For The Problem?

Hi. I have played softball for about 8 years. I was the only pitcher on my team for 4 of the years, causing me to pitch every single game. Last summer, i was at a showcase&my arm just gave out on me. I couldn t throw the ball, couldn t do my hair, couldn t open the door, couldn t do anything. I rested it for about 4 months and went to play high school ball, pitching every game. Doctors told me it could be an infringed nerve but I dont know for sure. After I pitch, my arm shakes, its gets really red amd swollen, and I cant write or grip anything. Also whenever I straighten my arm out, I get shocks to my hand . Its a really words injury. What could it be and what can I do to fix it?