As @seniormed mentioned, inflammation of the tendons and ligaments could be a symptom of many different conditions…

I’m not very familiar with undifferentiated connective tissue disease, but from what I searched, I didn’t really see that mentioned. I have seronegative spondyloarthropathy, and a hallmark symptom of it is enthesitis (inflammation at the insertion points where the tendons go into the bone at the joints).

It sort of sounds like something that can be mistaken for UCTD or vice versa because inflammation of the tendons wouldn’t be visible on imaging (except ultrasound, sometimes) for years after having joint damage. And I have the seronegative variety which means my inflammatory markers are not elevated. I just have the pain. At the beginning, it’s often mistaken for being a tendon overuse injury.

Can you ask your rheumatologist if it may be related to your current diagnoses?