Torn acl or knee injury?

OK so yesterday I was getting up from my bed, and all of a sudden my knee gave out, and my leg twisted and I fell to the ground. My knee started to swell and it felt like it had been hit by a slege hammer. Every time I moved it I got a suging pain that jolted up my leg. I raised it, and put Ice on it, and went to bed. Now it is a little better, but there is still constant pain and all movement hurts. The swelling is the same and I have been taking advil and continuing to ice it. When ever I try to move around, I have to move very slowly, and I have to lock my leg to keep me from falling. I can not hold myself up with a bent knee like the other. I don't know why this would happen, but me weighting 260 doesn't help. I am not fat, alittle husky, but I am 6'3.5'' and I have big bones. I don't play many sports but painball and golf. I called my doctor and they said wait on it, they thought it was probably shifting cartilage mixed with the slam my knee made with the floor. Do I need to have any worries about having to get surgery, or should it heal up on its own?