My cycle hasn't been regular in recent months, the last cycle lasted almost 10 days it ended on the 22nd Aug, Ihad sex on the 23rd and again a few days later, I started spotting, like that before periods on the 2nd Sep, the bleeding grew and was enough to wear a pad and the flow was equivalent to my Normal period flow, I stopped wearing a pad the day before , it's the 11th today and I has this small clot in the evening, haven't had since, what can be the causes.