Hi, I Am A 33 Year Female, No Kids, Sexually

hi,

I am a 33 year female, no kids, sexually active with only one partner. I had a clear papa test in March 2015. I used to bleed a little after sex, and it wasn't clear why, but got an ultrasound and it came out fine, the doctor had also recommended a vaginal ultrasound but I did not get that done. I assumed perhaps it was vaginal dryness, now recently I've started spotting multiple days, and usually more when there is a bowel movement. I can confirm though that the blood is vaginal. My periods are regular and come every month, on the same day and last about 3 days. I am not sure if this is something I should be worried about. I am not on any contraceptives