Today i woke up with really bad pains HELP?

Question

last night the backs of my knees were starting to kind of cramp up and i didnt think anything of it. when i woke up today i was in horrible pain i could barely walk i couldnt extend my legs. it went away but now it is starting to come back

any idea of what it is

Answer 1

growing pains lol?

Answer 2

Have you done anything different in the last day or two? Any unexpected exercise? Any injury? New shoes?

More than likely there would be an obvious answer for this.

Lloyd