upset stomach vs stomach upset

upset stomach and stomach upset both are nouns.

Word	Noun	Adjective	Verb	Adverb
upset stomach	Yes	No	No	No
stomach upset	Yes	No	No	No

As nouns, upset stomach and stomach upset are synonyms defined as:

upset stomach and stomach upset: a disorder of digestive function characterized by discomfort or heartburn or nausea

Other synonyms of upset stomach include dyspepsia, indigestion.

upset stomach (noun)	stomach upset (noun)
a disorder of digestive function characterized by discomfort or heartburn or nausea	a disorder of digestive function characterized by discomfort or heartburn or nausea