You can tell a lot of the guys in this post don't train, mostly by their comments about heel hooks. Heel hooks are forbidden in many schools because they don't hurt until they do damage. When they are applied they target the knee not the heel (the heel is used as a lever to manipulate the knee). One small disclaimer is occasionally you will feel a small "tweak" in your knee if it's applied without damage provided you tap before they go any further.
-Best of luck in the future, and keep training.