My Knee Is Hurting

Tonight is the worst night ever!My lower thigh and also my knee is hurting badly from which I do not know why.Should I go to see a sepcialst about it?The worst part that has been hit by this anonymous pain is around the knee area,which when sometimes I walk,there's this painful sensation like something is in there,poking my knee cap...Hmmmm some people might say that this is the cause of me too exhausted out of playing soccer or something,but it is not.Today,in fact the whole day I spend it at home,sitting and laying down.This has no direct link to my pain.Can anyone tell me why am I hurting this bad?