What Causes Intermittent Right Arm Pain And Swelling When Diagnosed With MRSA?

I had a picc line in for ten days. It s been about a year now, and my right arm has given me on again off again pain. Two weeks after I had it removed, I went to my local ER, and they said it was just some swelling. Now my arm is hurting from the elbow and the way up to my under arm. I have several sores, they culture positive for MRSA, as I got it during a surgery back in 2013. I am told the MRSA is in my body, not the blood stream. And my right arm that the picc line was removed about a year ago, it will make a year come September of this year. My arm has sores/abcess looks like out line under the skin in some areas of picc line. I have had an x-ray, ultra sound and echo cardio gram, and none show picc line present. Just swelling/fluid. And say MRSA is the cause. Can it still be picc line still there and they are not seeing it even after all the tests?