I am a 25 year old female and have a period that has been late for 4 days. 3 weeks ago was the last time i had sex with a condom, and i am not on birth control. Since then i have been through alot of stress in school as it is finals and i have clinical placements for my degree. i have noticed that my bowels of changed, going from constipation to diarrhea. i have dull pain in my lower abdomen, and i will sometimes feel a little nauseous but not "stomach churning". I do not have breast tenderness at all, nor do i frequently urinate, but i do find myself going to the bathroom just to check if there is any blood. I have come to the point where I have psyched myself out that I dont know if I am experiencing PMS or something else. Please help, should i be concerned or is the late period due to fasting/ stress. thank you!