Knee weakness after pain

[Hmpher]

I think there might be something wrong with my knee but not sure whether it needs medical attention (at some point) or just a thing which happens to people sometimes.

About two weeks ago I became aware of my knee hurting. I didn’t injure it or bang it as far as I know, it just started to hurt one day. I thought I must have slept on it funny and it’d get better, but it didn’t. I was limping a bit because putting weight on it was painful and made me yelp if I accidentally did it, particularly if I was putting weight on it from a bent to a straight position, such as getting up from sitting on the floor or walking up the stairs. Two weeks on and it barely hurts anymore but it feels like it’s about to give way and bend backwards. It did bend backwards slightly last night when I stood up which was very unpleasant. My knee has also been making a clicking/crunching sound if I bend it, but again, it doesn’t hurt.

My sister is hypermobile and she was told that I’m likely the same because there is a family link and I can touch the floor with my palms without bending my knees/bend my thumb back to touch my arm, but this has never caused me any problems. Could this be linked? It seems really odd that I was limping and feeling so much pain without having injured it in the first place.