Thank you for your query at DoctorSpring.com
I understand your concern.
Such progressive joint pain is indicative of Rheumatoid arthritis, however that has been ruled out.
So I need to see reports for the following tests : complete blood count, sedimentation rate and CRP for inflammation,ANA (test for lupus), urinalysis, TSH, T3, and T4 ( Thyroid panel ).
You said inflammatory markers are elevated. Will you mind uploading all your reports? That will give a better idea. And whatever tests you missed out, from the tests I advised, also needs to be done.
If you have difficulties uploading the report here, you can mail them directly to firstname.lastname@example.org
Once I see your reports, I will get back to you.