we started p90x on friday and ever since i did yoga yesterday my knees have been hurting a lot, like i twisted something. i have always had problems with my knees so this is normal to me, just wondering if i should keep pushing myself through the workouts or do something else instead like a workout i know i can do. i can most of the workouts with my knee like this but i cant bend my knee so thats a problem, so should i do the workout i had previously done while they do the current workout. please help tomorrow is legs and back.