Could be something as simple as gout. Was for me. Years ago I was in horriffic pain with both knees. About the time I went into rehab. For 13 years I was sober and never had a problem.
Started to drink again 13 years later...and the gout and pain came right back!
That was 17 years ago. I've had a gout attack about every 3 months or so. I just cant seem to learn.
Beer is the worse thing to cause gout...but ANY alcohol will trigger it.
Just saying...
OH....and a MRI doesnt "miss" anything...IF read properly by qualified personel...usually a certified Radiologist...or a Specialty Physician.
Hope this helps.
DD