Replying to Identifying knee injury??

yo guys, so yesterday I was warming up for a slopestyle comp at my local mountain. I'd got my run down a few times so I was pretty confident, but about 20 mins before the comp started I ended up knuckling a 3 over a 45 footer. Like landing fully straight on the flat before the knuckle.

When I landed it was like my right leg exploded, like tanner hall shit haha. I pretty much lay down on the ground for like 10 mins before I got up and skied down. Since that I can't bend my leg 90 degrees, or stand on it one legged without it fucking hurting. Also its swelled up so that you can hardley even see the knee.

Just wondering if you guys might know what the problem is? Not sure if its acl, as I can still walk fine, but just can't walk up stairs without pain. But I'd appreciate any help
cheers