system
A chat on subreddit /r/me_irl
human
I've definitely had an achy testicle. Very nerve-racking. Glad everything was ok with you.
gpt
While many might not think it first thought you can pull a muscle in your groin/pelvis or even get the nerves tangled just like you would your back, or any other muscles. It will make ya testicles achy (but its more likely it's your groin thats achy) and you will have a queasy stomach - same feeling of getting hit in the testicles. Most of the time if your pain goes away with laying down or heat - it's a pulled muscle. 

You will feel like you are literally dying if you get torsion - not just a sense of achy doom. But any worries should be checked out by a doctor.

Also fun testicle fact: your testicles can also hurt if you damage your vagal nerve/vagus nerve from coughing too hard from a bong hit, or pooping too hard after eating flaming hot cheetos, or stretching your neck wrong after watching a television show for hours on end. You wouldn't think it be how it is but it do.