I agree with eric. See a doctor and don't play around with your shoulders at all. If they are giving you a problem while lifting then definitely stop and seek advice or council from a doctor. I made the mistake of not doing that and I have had to have 4 surgeries on my shoulders....and maybe more in the future.

Working out is highly dependant on your arms and shoulders. Almost all muscle groups require some use of the arms either for stability in holding the weights such as squats or lifting the actual weights themselves. If those go or give you problems, seek help immediately.