why do my balls hurt so much?

It's probably because you are getting aroused but not having a release. It's called blue balls. Try to distract yourself with heavy exercise or deep intellectual work that will take your mind off of sex.

 

Be sure you are not edging, that can cause blue balls as well.

 

Mine sort of ache occasionally, not much though. It's probably because they are getting full.

 

Yeah. Every time I have had this, it is because I edged real hard for 30 mins or more.

 

I agree with the comments here. It's about congestion and build up of fluids not only in the testicles, but in the epididymis and vas deferens where most sperm is stored as well as the prostate gland. I don't know if you also notice that you'll start getting leaky during this time as well. Don't edge and gain control, as edging will just make it worse. If you're lucky enough, a wet dream can help relieve.

But if it's really painful, you have to get it checked. If not, you need to keep busy and all. No fapping!