Pill side effects or pregnancy.

3 months ago I was switched from the orthotricyclen birth control pills that I was on for over a year, to the generic Trinessa Lo pills. I began my third pack of the generics a week ago from this past Saturday. I take the pills around the same time, at night. That night, I took the pill, & in the middle of sleeping I woke up nauseous. Since then, day & night, I've had mild nausea/indigestion type uneasiness with my stomach. I haven't thrown up, at all. Could it possibly be my pills side effects catching up with me, a slight stomach bug or could I be pregnant even if I have no other pregnancy symptoms? (No skipped period, etc.) just wondering before I try to get in with my doctor.