Going through suspected knee bursitis here. Had a weird minor swelling like I'd bumped the knee and then managed to do a suspected minor meniscus tear, which might have masked the bursitis issue. About 3 weeks later, with knee virtually pain free, I was out on a light hike with the dog, when the area below my kneecap swelled up to like 1/2 egg sized.
Physio agreed that it was most likely bursitis, the temp doctor (my regular GP was away) agreed, but wanted me to complete a course of naproxen first. (This was the second time I saw him on the issue, first time was "well, just rest", which is just about the worst advice ever).
Completed that, knee still feels like at 70%. I can do most things, but it will get 'angry' if I push it and I need to ease off for a few days.
Spoke to my regular GP today, she's reluctant to go to corticosteroid injections and now wants an x-ray. Amazingly there's a couple of new walk-in imaging clinics and it took 10 mins, so I'll book a new appointment at the end of the week with the doc.
It's been extra annoying as it happened just before my 2 month break from work, where I had planned to A) get fit again B) do a bunch of renos, and neither has been possible with the knee buggered up. I'm close to buying a trainer for my bike, but I've always hated those things.