What is wrong with my knees?

Whenever I do a squat or a lunge both of my knees hurt pretty bad. Not so much when I’m going down more when I’m coming up.

Things to consider:

I’m young (not too young)

I do gymnastics for 12 hours a week

After I do the training that hurts my knees it doesn’t go away until around 1-2 hours later

I have broken the growth plate around the other part of my right knee