Hamstring cramp

So, today I was standing on one leg and I pulled the toes of my other leg to my butt and I got a very panful cramp.

 

I don't get cramps otherwise, but there is a clicking noise when I flex my knee between 45° and full extension.

 

Also, when I squat low, I get a grinding sound at the same ROM.

 

Is this a result of poor flexibility or maybe hamstring strength? My quads are stronger than my hamstrings, so it might be an imbalance.  I'm testing mastery of PE3 this week, but I don't exactly have weak legs and I'll probably be moving on soon.

 

(P.S.: I'm already scared of SE1>iM )

Cramps happen when you contract a muscle already placed in a shortened position.

It has nothing to do with imbalances or noises in your joints.

 

Thanks for the answer, I should probably read more on cramps .

 

Should I be worried about the noises tho? Do I need to see a doctor or is this a harmless thing?