Two months means it's not muscle. Probably tendon or ligament. If the tendon or ligament is not torn and is only 'out of place', I would suggest a chiropractor. In my experience this kind of thing can be resolved with only one adjustment. However, if a tear is involved, either wait it out and see OR go to an orthopedic doctor....he will likely recommend surgery to repair the tendon or ligament.
One DIY thing you could do at home would be infra-red treatment to reduce pain and speed up natural healing...even for tears. Some rehab facilities will offer infra-red treatments when prescribed by a doctor....but its going to take take time out of your day, several days a week. A few years ago, when I learned, through personal experience, how well infra-red therapy worked, I purchase my very own re-furbished infra-red therapy device from "Anondye Therapy." >>>
http://www.anodynetherapy.com/ <<< This is not 'new age voodoo'. It's been used in veterinary medicine for a long time with outstanding results. It's been a very good investment for me.