I've got a blood test done on me about 8 days ago it was 4 vials and it was on my left arm. As of now I have a somewhat small bruise on my vein where they took the blood the nurse got me on the first time cause my veins are very noticeable. If I poke my vein it hurts a little but what's really bothering me is my arm and hand, say if im playing a video game my muscles in my upper and lower arm and hand start to feel tight and start to ache even sometimes when I'm not doing anything my muscles on my arm feel tense as if I over worked them. Especially when I stretch out my arm it hurts. What could be the problem? It is something I should be worried about? I've been in and out of the E.R. And doctors for thyroid issues (everything started june) and I don't want to go back if its not a big problem.