Hi, According to your history the possibility of pregnancy is less usually. But if you are having a short length of menstrual cycles there is a possibility of early ovulation, in that case as you were not on pills and third time there is some possibility of pregnancy. According to your symptoms, the other possibilities are pelvic infection which can present with abdominal cramps, fatigue, headache and sometimes spotting. In the middle of the cycle during ovulation also sometimes this type of symptoms can be seen due to the drop in reproductive hormone levels. If you want to exclude the possibility of pregnancy, please go for a blood test for pregnancy after three weeks of unprotected intercourse. If the symptoms persist, please consult your gynecologist once and get examined to rule out the possibility of pelvic infection and take treatment accordingly. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Sree Gouri S. R., OBGYN