Thanks for your query.
Noted the history and understood the concerns.
With the description that you have given the possible causes are:Rheumatoid arthritis
Hence I would advise you further tests of blood in addition to MRI:
CBC with ESR
RA factor that is Rheumatoid factor
Calcium and as needed.
Clinical evaluation by a Rheumatologist
All these will lead to a proper diagnosis for getting the exact treatment.
Do the warm compresses in saturated salt solution to be more effective.
Take an anti-inflammatory medications with pain killer properties as might have been prescribed by your Doctor.
I hope this answer helps you.
Please post photos of the lesions as it helps sometimes for on-the-spot diagnosis.
And post reports of the investigations.