hey thanks for the VM, I had Osgood Schlatter when I was younger and yeah, my current condition certainly feels similar to how that felt. Similar kind of burning pain, but while I could train through Osgood I cannot train through this as my leg has become far too weak due to the degeneration. Can barely walk up the stairs without stopping for a break halfway.
The OS moved seamlessly into the tendonitis so I didn't know I even had tendonitis until it had became chronic and the doctors, in their infinite wisdom, thought the best treatment would be steroids (as they're potent anti-inflammatories) but they hadn't realised that at the time, I had tendonosis, not tendonitis (sound similar but different, tendonitis is inflammation of the tendon, tendonosis is degeneration of the tendon). Whereas steroids are great for tendonitis, they're akin to injecting a pirhana fish into your knee as far as tendonisis is concerned as they just further weaken the tendon. By the time they realised, it was too late. I was offered a reconstructive surgery but they estimated a 30% success rate, with a 10% chance of it actually making it worse so I rejected it.
I'm working on building it back up through eccentric exercises, good diet and plenty of rest...I'm determined I'll run again eventually (love it too much to just give up on it) but I have to come to terms with the fact that I'll probably never be able to run as well as I could prior to the injury (still gonna try tbh, I just have to see how things work out over the next year or so).