Had sex 3 days ago and yesterday im on birth control and take it timely every day. this morning i woke up with nausea and a stomach ache any way its because of pregnancy? i think it may be a stomach bug with me having went out to eat yesterday?

It is difficult to determine the exact cause of the nausea and stomach ache. While pregnancy is a possibility, it is important to consider other factors such as a stomach bug or food poisoning from eating out. It is also worth noting that birth control pills are not 100% effective at preventing pregnancy, so there is still a chance of pregnancy even when taking them correctly.