I've tore my acl and meniscus and i was working out then it just started swelling and bothering me at the back does this mean i re tore something ?

Not necessarily: This could be caused by over stretching one of the ligaments, not necessarily a tear. It could also represent a hamstring injury or even a popliteal cyst at the back of the knee called a Baker's cyst. Of course, it could be more meniscal damage or tear. Rest it, avoid aggravating activities, ice it. If the swelling and pain persist after a few days, see your doctor. Good wishes:)