shoulder, wrist and forearm pain

[remainmobile]

In the past I had pain in my left shoulder(im assuming its shoulder bursitis, but im not sure) when I would do bench press. I currently work at a library which usually includes repetitive motion of the same kind. A few weeks ago my wrist started hurting really bad if i curved my hand inward(my fingers towards the underside of my forearm). Im wondering if this is tendonitis? I bought a brace, which helps tremendously when I am working, but I have had times where I forgot my brace and was straightening books and almost my entire left arm has a slight pain(left forearm, left wrist, and left shoulder). The pain is not unbearable, but I took a break of working out after it was injured, and then went back to working out, which im thinking might be a bad idea. I guess my question is, what can I do for recovery of this in a way that will preserve the most muscle possible as well allow time for my shoulder and wrist to heal? Are there supplements I should take for it/for preserving muscle?

thanks for any help