I Had An Injury Seven Weeks Ago.. I Was On

I had an injury seven weeks ago.. I was on a swing and my grandchild was on the other. She is three years old. We were both going high when she decided to jump off the swing and head towards the road. I stuck my leg out to stop my swing and ever since have been I really bad pain. X-rays and MRI don't really show much. Had my knee drained and have been getting massages, but not getting better. Muscles and tendons are all tight. I have a knee replacement in the other leg and have to have it redone and am worried about what is going on with this new injury. Can't seem to get better. I am going to be 70 next month and am in good health otherwise. Any suggestions? Knee is still swollen and can't bend it back all the way. Also going to pt and doing stretches. Thank I for ur time.