You should call your doctor. It's better to be seen and everything be okay than to possibly ignore something important. I hope you feel better, but do still call your doctor.
Is it sudden back pain and cramps? It could be BH contractions caused from the throwing up. Whenever I threw up I got contractions. If they get really painful or worse I'd call your doctor and mention it, see if he/she is worried, if they are they'll have you come in