Two weeks ago I tripped over an extension lead at work and skinned my knee. There was quite a large scrape on the knee, and it was a bit swollen. As it happens, my doctor's surgery was open and on my way home, so I stopped off to see whether I'd seriously injured myself.
The doctor said that there was no serious injury, just 'Parson's knee'. He put a new dressing on the scrape and sent me on my way with no particular advice.
The next day the knee was swollen and sore, and I limped and struggled through my day, which as usual involved going up and down stairs. By the end of the day, not only was my knee swollen and sore, but my foot also was swollen. The top of my foot hurt when touched.
The foot stayed swollen until last weekend, when someone finally told me to elevate it as much as possible. It's now returned to normal and no longer hurts when touched. But my knee still hurts and there is still swelling below the patella.
I've already got one bad knee (Osgood-Schatters when I was young). I'm now beginning to worry that I've got another.