weird orrrrr ?

Josephine
So about 10 days ago my boyfriend and I had sex it was normal/no protection and I am not on the pill. So two days ago I was "bleeding" very very light pink. Still till today it's very light pink I'm sort of confused because by this time it's usually heavy and my regular period only last four days even if my cycle is irregular. Has this happened to anyone before? Any idea of what happening? Should I see a doctor lol