What Causes Pain And Clicking On Knees?

I am having current knee pain in both knees and recently I was judging an event for the military and had to stand in boots for 10.5 hours and could barley walk without knee pain after that I am having clicking in both knees. I am in the military and run in boots allot and I was also wondering do orthopedics recommend the Donjoy braces for military personnel during running and other activities