Hello, I would be happy to help you with your question.
Never assume that just because you are on birth control that you cannot be pregnant. No birth control is 100% effective. Part of the sorting out of your symptoms should definitely include a pregnancy
test. You might simply have a viral GI illness. You should stay hydrated and take it easy. If there are any other symptoms, such as heart racing or palpitations, you need to see your doctor.
I hope that this helps. Good luck!