I heard this on my radio last night and just looked it up. Can't help but think that I went thru 2.5 months of undiagnosed staph infection in my knee when finally doctors sent me for MRI which showed the infection. I did NOT walk for 2.5 months with that raging infection, feared I would not walk again. Scary stuff...very scary. If there could be something going on with you don't disregard infection possibility. All the doctors and I were thinking arthritic issues and it was a raging infection. I'm not a fear monger person but my experience was life changing and thought changing.