EXTREME KNEE PAIN

I am 32 years old and I teach taekwondo. recently (3 days ago) i was teaching a class and doing some leg strengthning exercises. One exercise was particularly stressful to my knees where you lift one leg off the ground and squat all the way to the ground and back up. anyway

This morning I was coming out of a van and as I turned to walk I got what can only be described as a burst of excrutiating pain to the front of my knee ( just under the knee cap in that little space where doctors tap to test reflexes). The pain would subside and then flare again to extreme proportions. This lasted approximately 1 minute then stopped.
It just happened to me again tonight as my legs were hanging off the bed under no strain whatsoever. Again it was excrutiating lasting 2 mins again in waves subsiding then extreme pain. What can this possibly be and how can i treat or minimise its occurance?

[daisey16]

my dad just got an operation, for torn cartilage on his knee, he was in pain, maybe you did the same, need MRI to confirm