I land on my right foot after my service motion, and although I don't feel anything at all on that day, the next day I feel absolutely horrid. After my crosscountry track workout (the day after), I felt a crippling pain shooting up behind my knee. It's persisted since yesterday, and I'm afraid it might prolong. I've had this pain before, though. Is this only because I'm not landing correctly? Should I land on my entire foot (heel to toe), land on the balls of my feet, or just bend my knees more to resist shock? ...or do I simply have a weak right leg?