Nausea (Latin nausea, from Greek ναυσίη, nausiē, "seasickness" "wamble" ^[1]), is a sensation of unease and discomfort in the upper stomach with an urge to vomit.^[2] An attack of nausea is known as a qualm.
The most common cause is gastroenteritis ( a stomach infection ) or food poisoning but nausea also frequently occurs as a medication side effect and in pregnancy. A number of medications exist that improve symptoms including: dimenhydrinate, metoclopramide, and ondansetron.

Well, I can rule out most of those...