My knee started really bothering me yesterday. It hurts very bad to bend and unbend(lots of pain). It doesnt hurt to bad to walk but does hurt to walk upstairs. My knee doesnt hurt to touch and there is minimal swelling. I dont know what to do but it is just unbearable to unbend and bend my knee which makes it very uncomfortable to sleep. I dont know what happended to it either and keep in mind im a 17 year old girl so i dont think its age related. Any suggestions please!