Slipped on ice out side..left leg went forward some thing popped...now large black n blue area from bak of knee up to below groin area..is it. normal?

Well, it is...: If u fell and pulled your hamstring tendon( most probable) or adductor muscle / tendon. Ecchymosis( black and blue discoloration ) is normal after you ' pull' or tear a muscle / tendon as it bleeds in the muscle and sq tissue. Rice( rest, ice, comp. Elevation ) is appropriate first 24-48 hrs. See your pcp for evaluation .Good luck!