Knee pain

Of course there is, dependant on your age, always the possibility of the onset of Arthur's Eye Test. I'm thinking of the Osteo flavour. Definitely not something to be dismissed without consideration. A visit to your regular Grand Prix driver may prove beneficial, if you can negotiate the 08:00 scramble, that is.

I have knee pain occasionally. It used to happen more when I had a single-speed. I can usually resolve it by using lower gears to spin more for a week or so. Ride slower, but keep the cadence up, 80 as a minimum.

If I had burning pain even off the bike after trying that, I'd probably take two or three days off cycling, take Ibuprofen (Naproxen), and ice it at least twice a day.

Are you riding in cleats?
Have they moved ... even fractionally?

Might be worth checking your cleat alignment, just in case one of them has moved.

I'd been having similar issues, and it turned out that one of my cleats had somehow slightly changed alignment, and it was causing a change in the rotation of my knee.

Check your cleats, maybe try your LBS for an alignment check, then speak to a physio.

I'd find a physio who would have a look. They will do tests to determine where the issue lies, the extent of mobility and maybe some exercises.

Adjustments may help with the symptoms but not resolve the underlying issue.