Osteosarcoma HELP me please!!!?

My Knee has been bothering me, it hurts when pressure is applied. Im really scared. Ive been worried for about a month now. somtimes I feel like it hurts when I dont put pressure on it or move it. It kinda hurts the whole leg. is this Osteosarcoma? what do I do?! Im really worried PLEASE ANWSER. and yes when I can I am going to the docter but please dont anwser with that.