Hello, If your period is light and late just for one month, it s not significant. AUB (abnormal uterine bleeding) is defined as a change in volume, regularity, or timing that has been present for 6 months or longer. The causes could be uterine polyp, adenomyosis, leiomyoma, malignancy and hyperplasia, endometrial disorders, ovulatory disorders, coagulopathy, or pelvic inflammatory disease. If there is an infection, it would be associated with fever, abdominal or pelvic and low back pain, and abnormal vaginal discharge. Sometimes burning micturition. But in your case, it seems to be mild hormonal disturbance and it gets corrected itself as you don t have much symptoms. As pregnancy test is negative, it is ruled out. For pain you can use tab. Meftal spas once daily for 3 days. For nausea, tab. Ondansetron 4mg would help. If the irregularity continues into next period, you may consult a gynecologist. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Pallavi M., Anesthesiologist