If it lasts for a while without going away, he needs to go to the Dr.
Several years ago, my DH had bad stomach pains for a few days. At first, we thought it was a stomach bug. DH promised to go to the dr. on Friday, if he was still sick. Of course, I came home from work and he hadn't even tried to go to the dr. That night, he was moaning and groaning so much that I couldn't sleep a wink. In the morning, I dragged him to the ER. His appendix had ruptured and was gangrenous. Without an appendectomy, he would have died in another couple of days. A usual appendectomy requires an overnight hospital stay. Because DH put things off and his stomach cavity had to be completely flushed of the gangrene, he spent 3 days in the hospital, in immense pain.
When in doubt, go to the doctor.