I've been fortunate to not have to deal with this but on a rare occasion and only for a short time.
I did come across and article that says an infection of the joint itself can cause inflammation and issues - but it's not taking into consideration the vector borne infections like Lyme - which we know can attack the joints and bones as well as soft tissues.
It may be just inflammation too. I hope your doc can be of help with this.
Herb only treatment for Lyme & Bart ended 12/11 - no active symptoms for 2 yrs -Herb only treatment for Babesia ended 12/12www.healingwell.com/community/default.aspx?f=30&m=2977364
Had Lyme, Bart, Babs, RMSF, Ehrlichia, Myco, Anaplasmosis, EBV
New Lyme case 8/2014 - Healed 1/31/15 - unknowingly had Asymptomatic Babs and Asymptomatic Bart, being treated now though (2/2016)