Feelings of nausea (even vomiting in some women) and cramping can most certainly occur when you are late with your period. Obviously you are stressed out about the possibility of being pregnant and stress can cause late periods. Try to relax, take a warm bath and see if that will bring it on. Meanwhile, if you are not on some type of birth control I suggest you see your doctor and if you are, thistoo can cause you to miss periods, have cramping and feel nauseated. Get your sexual partner to ALWAYS wear a condom to protect you from sexually transmitted diseases. If you haven't started your period by the end of the month then please see your doctor.