I had my period on september 22, then oct 31, n then december 6. So the gap was around 30 to 40 days. But after dec 6 i again had it only about 2 weeks later on dec 24 which lasted less than 3 days. I had oral sex on the morning of jan1 N then again i had my period on the same day later only after one week. At first i thought it was just bleeding externally. But it was accompanied with back pain which happens to me during my period. N im still bleeding but its not as much as it used to during my normal periods. Why is this happening?