Hi, According to your description the possibilities are: - Hormonal imbalance, which can lead to scanty periods and Premenstrual syndrome with headache, pain abdomen and breast tenderness etc. - Sometimes urine pregnancy test kit can give false negatives in early pregnancy. Here especially you have to rule out ectopic pregnancy as you are having scanty bleeding associated with pain at sides of the abdomen. So, if the symptoms persist, please consult your gynecologist once and go for ultrasound and if needed serum beta HCG levels, this will help in ruling out the possibility cause of ectopic pregnancy and also in finding out the possible cause of the problem. If hormonal imbalance is found to be the cause, analgesic drugs, hormonal pills can help in in relieving the symptoms. Drugs containing evening primrose oil can also give symptomatic relief. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Sree Gouri S. R., OBGYN