What Causes Brownish Red Vaginal Bleeding After Taking I-pill?

I am married recently. I had sex with my wife. Usually she has her period from 21st to 27th. We had sex on 30th night. I didn't use condom and didn't ejaculated inside her. But to b safe i went to medical store and he gave me ipill. After i gave ipill on 31st morning. She is having bleeding like chocolate red blood. Its still happening. not much & she is not feeling pain. Please advise me what to do? We don't want baby now. I don't want to harm her body. Your help will be appreciated. Thanks