What Causes Pain In The Upper Right Arm After Upper Spine Surgery?

Thank you, I have had recent surgery to replace three discs in upper spine I believe c4, c5, c7, This was performed due to off and on recurring neck and shoulder pain for over thirty years. Almost always on my left side. Prior to the surgery I was seeing a chiropractor and I developed a what I felt was a different type of pain in my upper right arm. The chiropractor, my own GP and the surgeon all thought it was related. The surgery was six weeks ago, went very well still some stiffness but I feel most of that old pain is no longer. The upper right arm is another story, that pain is the same and very sore. I do have a lump under the skin at the spot of the pain (Not sore to touch or anything). All dismissed this!!!! I am still taking oxy codone that was prescribed after the surgery but that only helps for a while. Could this pain be rotator or something else really concerned and in a lot of pain. See my surgeon on the 28th. Thank you in advance for any help, John S,