How Can severe Shoulder Pain Be Treated?

I have pain in my right shoulder that later turned into what appeared to be stabbing very intense pain in my side, but hurt to touch on my scapula and radiated towards the side and under neath my rib. The pain on the side has improved but it still hurts to cough or when I strain to go to the toilet. Also, I now have pain on BOTH shoulders. I notice I have more shoulder pain now on both shoulders after purchasing another mattress which originally was intended to relieve my side pain which was excruciating. I was seen in a urgent care clinic and prescribed gabapentin and flexural as well as norco, in which I am not taking at this time but did for 2 days. I wake up at night with shoulder pain and neck pain, but now I am noticing I am starting to get back pain as well. Could it be a pinched nerve and how do I know if that is the case?