Hi,
Other than being a sign of pregnancy, the icy-hot sensation sometimes can be due to nerves (anxiety or stress), or an illness (flu, etc.), or even indigestion. If you haven't been sexually active with your boyfriend, then you shouldn't be worried about being pregnant. Try to relax by taking it easy w/ your feet up, and apply warm, damp heat to your abdomen to relieve any soreness. You could always take a pregnancy test, if you think there's been a risk. If the test is negative, and you continue to feel discomfort, make an appointment to see your doctor for a wellness check. I hope you feel better soon :)