To alleviate shoulder pain take some aspirin as well as a nice long hot shower.
The hotter the water you can stand it the better.
I also recommend using a hand held massager or having someone massage your shoulders which will help with shoulder pain.
You should also see a doctor and they will likely take an x ray of your shoulder to be sure nothing else more serious is going on.
They might recommend shoulder surgery to repair anything that might need repairing in your shoulder that could be causing the pain.
Then again it might be something less serious in which they might only have you take some pain medicine to ward off the shoulder pain.
In the mean time avoid lifting anything too heavy with that arm.