My Medial Cubital Vein Area Is Swollen. When I Touch

My medial cubital vein area is swollen. When I touch the outside, I don't feel anything, but it hurts inside. And my fingers on that arm feel as if pins are poking it. There's a big bump, and that area on my arm is where doctors draw out my blood. I can't use any power with that arm and if I do, my arm feels really weak. What's going on?