i have had pain in my right arm for about 3 months, sometimes my shoulder hurts too. it is worse in the mornings. i have had test for rheumatoid arthritis , but they have come back negative. other tests, such as test for kidney problems etc. have come back negative. i still have the pain, and have difficulty in raising my right arm. my doctor gave me a steroid injection, and the pain is a little better, but it has not gone away. how long will the relief from the injection last ?