Having random spells of nausea. i haven't eaten anything out of the ordinary and i religiously take my birth control so i know i'm not pregnant.

Don't be too sure...: The GI tract has a very limited # of symptoms to signal its distress--nausea/vomiting, diarrhea/constipation, bloating, pain, fullness, bleeding, etc. As you know, many of these characterize ibs, but are also seen with inflammatory, infectious, ischemic, malabsorptive, and functional disorders. Also, pregnancy is always possible despite use of birth control--no single method is 100% effective.