I had a problem with one of my knees for a few years. MRI, several doctors etc, and no closer to knowing what the issue was. It affected my ability to do most physical exercise, and though it wasn't always painful, I was alway worried that it would be at any moment. I finally cured it completely with the aid of a GOOD physiotherapist and a lot of rehab on my part. While symptoms presented in my glutes (tightness etc), I needed a crap-ton of core work and work on posture ... a few months later and voila! No issues. Though the rehab work will likely be a lifelong thing, it has been easy enough to incorporate into my daily routine. Yoga is a key component of this.
So yes, see a doctor, get another MRI if you can, but also track down a good physiotherapist who is active themselves.