About 3 weeks or so ago I got up outta my chair to go upstairs and thought i was just sitting wrong because it hurt a little going up the stairs, but coming down the stairs it felt like the inside of my knee was just on fire and immediately swollen. i ended up dropping everything and almost falling down the stairs, being a mother with very limited transportation i just loaded up on tylenol and rode it out hoping i just pulled something...about a week i had troubles getting up and down stairs, bending my leg, sitting, laying..anything that would make me lift that leg or bend it, but to stand on it it really didnt hurt. about a week the pain went away but a week or so later somehow it started up again and then the other day i had to walk up a big hill, got home and since then my knee has been severely swollen and when i go to bend it, it feels like something is grinding and a lot of pressure...is this serious or did i just pull something?