I have terrible knees ...
I have injured both knees alot over the years ... working and training horses. Accidents while moving and herding sheep ... in other words work related stuff that happens to all of us farmers and ranchers.
Crap happens ...
Mine do what yours is doing at least once or twice a year and I'm 58 1/2!
I will try to stay off of it for a little tiny bit of time but here that is nearly not possible. I still go out and do chores when running a fever!
Lots of people tell me to ice stuff but I can NOT do that! For me ice does NOT help but makes matters worse ... much worse. I have Raynard's and can NOT tolerate the cold.
Get either a heating pad or one of the little instant heat relievers that you can get at any drug store. I wrap my knee in that, then put one of the vetwraps on it and keep it up as much as I can. Before I wrap it I put either Arnica jel or cream on it/ OR some horse goo for sprains and such. I only do the horse goo IF it is really, really swollen.
Give it a couple of days ... soaking it in Epsoms Salts will also help. If you still can not bend it after four or five days of the above ... then you should maybe think about seeing someone.
Do you have Arnica tablets? I also take those when my knees act up.
Time is a GREAT healer!
"Any society which suppresses the heritage of its conquered minorities, prevents their history or denies them their symbols, has sown the seeds of their own destruction".
Sir William Wallace