Sounds like a prostate problem. Men have an extra "valve" that women lack. It sounds like classical protate problems. It will not get better on it's own and he needs to see his physician before it progresses.
Could be a kidney stone. He should see his primary doctor or a urologist soon.
Sounds like this could be a prostate problem or something going on with his urethra.
I would recommend consulting a Urologist to help him sort this out.
You need to get him an appointment with his doctor today. This is urgent.