Pain in knee under knee cap

I got a strange pain in the knee a few months ago and I have continued training because I thought it was just that my legs didn’t fully recover between training sessions.

Anyway in both legs I have a pain under the knee cap, just about where the patella ends i.e. where there is a small lump in the bone. I can run just fine, but after the run I feel a strong pain in that location when I try to stand up from a chair. It has also been impossible to squat.

I’ve got this pain in my both knees, so it’s quite disturbing. Anyone know what it could be?