To get an upset stomach; to suffer from stomach trouble such as diarrhea or abdominal pain.
昨夜食べたものが合わなくて、今朝からお腹を壊している。
Something I ate last night didn't agree with me, and I've had an upset stomach since this morning.
旅行中にお腹を壊すと大変だから、食べ物には気をつけてね。
If you get an upset stomach while traveling it's troublesome, so be careful with what you eat.
冷たい飲み物をたくさん飲んでお腹を壊した。
I drank a lot of cold drinks and upset my stomach.