From Longman Dictionary of Contemporary Englishstomach upsetstomach upsetMIan illness that affects the stomach and makes you feel sick → upset
Examples from the Corpus
stomach upset• In general, children and adults should not be given too much milk to drink if they are recovering from a stomach upset.• If you had a stomach upset you were sent to Mrs. Sutton who sold you a powder for tuppence.• John King makes a late shuffle after Neil McNab goes down with a stomach upset.• Carbon monoxide can cause headaches and stomach upsets or, at worse, be fatal.• Some even insert caffeine suppositories before a race in an attempt to provide a sustained dose with no stomach upset.• Additionally, many people report stomach upsets, ear infections and rashes after coming into contact with the lake water.• The cold symptoms, the stomach upset, the fevers all pointed to flu. 