Muscles are the main contractile element, tendons are there to anchor the insertion into the bone and not split apart. When want to reduce tension on the tendon you want to reduce the muscle belly spazm aka lengthen the muscles.
Practitioners have been getting it wrong for years by working out the IT band... Yes it's sore but rolling out an IT band actually does nothing, you're more than likely hitting myofascial junctions of your quads.
To effectively and efficiently address IT band problems you absolutely must look at glutes and TFL before you ever look at the IT band.
IT band is the area of pain but the cause of that pain is in the muscles.
Go get imaging on your low back. You don't have to take a prescription like most MD's will prescribe but there's no point in beginning rehab unless you know what the problem is. So if you have a frigging pars fracture, it changes the ball game completely.
Also bird dog, glute bridges, cat camel, side bridges, dead bug in their primary stages are full back rehab exercises. They get people better for a reason, but you need someone to progress you through them. TIred of people starting at the hardest variations and saying it hurt. Well no shit, because 99% of the population can't do the hardest variations