Hi, I too, was heavily into exercise in my day! My Rhumy says do not put excess strain on joints. He says walking is the best exercise and he recommends certain stretching exercise(usually while laying down) for certain joints. I was dx with lupus 11 years ago, but feel I had it much longer. It is life changing, especially when you are used to being active and the fatique takes over. Sounds like you are having a flare-up. Take it easy and rest as much as possible. The pain in left side could be due to running. Sometimes, it takes awhile for flares to pass. When I was first dx, people would say just spend a few weeks in bed, you will feel better. Unfortunately, Lupus does not work that way. I know exercise helps you feel better emotionally. Follow your MDs advice, hopefully he knows whats best. For me the pain is always there, but the degree varies. When I am under stress it is at it's worse. Sending you good thoughts, Rose