What causes gas to be trapped in the stomach? does it cause difficulty to break wind?

my husband suffers severe stomach cramps and flatulence every month. it occurs especially during the full moon days.it is so intense that even talking and slight movements also cause a lot of pain. this pain stays for 2 to 3 days n gradually subsides.he smokes n drinks regularly. what could be the problem that he is suffering from? is there any treatment?