Please! 
I'm mid-50s and have had increasingly sore knees, right one in particular over the past few years. Quite stiff in the mornings, easing during the day, often not evident at all but stairs are painful. My GP sort of shrugged and called it arthritis (I was there for back pain, not my knee, which turned out to be a crush fracture! Not osteoporosic).
Anyway, I did some not-very energetic dancing last night, more of a polite sway
and no, I wasn't p*ssed, but this morning, my right knee is agony! I can barely weight bear, and the only comfortable position I can find is sitting or lying down with my knee supported and bent quite sharply! I had to come downstairs on my bottom!
It's not hot, red or swollen, so, is it a sudden, massive flare up of arthritis, a torn ligament or a meniscus, and what should I do? Apart from ibuprofen, which I've taken. I don't think I can drive, though DH is here.
I hate a fuss but if it's like this tomorrow, I'm not sure I can go to work which will be a disaster as I am a HCP, on my feet all day, and they have no staff.
There is no point whatsoever in 'contacting my GP'. Currently non-very-urgent appointments are taking a good 3 weeks. But is minor injuries worthwhile? Staffed largely by nurses, which I have no issue with!
I know plenty of people go to Emergency with a knee so painful they can barely walk, but is that appropriate? But I do need a watertight reason IF I can't get to work, or do my job tomorrow.
I am trying to gently mobilise it today but I'm not sure it's helping at all!
Any ideas?