Replying to Water on the knee

So yeah today i was skiing at a hill i didnt really knew and hmm i saw a C box which was pretty wierdly set up
so yesterday and otday i tried it and either i cleaned it pretty nice or i fell pretty hard on it. idk why
so on the last run (yeah my friend called it) i completely smacked myself on the corner of it and then i think my knee knocked on the ground, which was pretty much ice.
3 hours later when i get out of the car (long ride home) my knee is as big as a tennis ball. my dad said it was water on the knee...
so yeah it sucks.....i dont know for how much time im out cause its the first time......any experience similar to mine???
anyone know if its just gonna go away without furter consequences?