Well. I have been hurting my right knee a little bit on dismounts. Today I landed on it a little hard, and it straightened and sort of hurt. So I tried to dismount onto my left foot. I don't even know why it went so badly. Possibly I dismounted when my right foot was close to the ground and my left foot and pedal were really high. I don't hurt myself very badly very often, but this was awful. I did that shock thing where it kind of doesn't hurt but it really, really does. I was practicing in the parking lot and when my leg crumpled away I just lay there for a minute. Then a driver pulled up, and stopped to check on me. I thought she was stopping because my unicycle was several feet away and together we were blocking the road, so I tried to crawl away from it to give her room. Apparently that looked really sad, because she started asking me how she could help really persistently and I had to insist that my house was literally visible from where I was laying. I did not add that I would be up to crawling home momentarily. I just said I'd be alright.
So eventually I climbed to my feet and gathered up my unicycle. I thought, hey, this pain isn't so bad. Probably the fear of dismounting will help me ride farther. I hopped back on, rode a little way, landed on my right foot, but the impact on my left knee, even though it landed second, was horrible. But not too horrible, I didn't have to lay in the street that time. Nonetheless, in the interest of keeping my knees functional, I came inside and curled up in a ball of pain, to study. Going upstairs to get water was awful, but I stretched and bent my legs and got them to where they only hurt very much if I stand with my knees unbent.
I do not really understand what went wrong so I do not know what to do, except stop riding until the twinges are gone.