I have a brown/black vaginal discharge that looks like blood. This discharge has occurred as a result of an over-the-counter treatment for yeast infections. Is this normal? What should I do about it?

Hello, Recently I thought I had a mycosis, since I had a thick white discharge, a little yellow, but not really itching and a little acid smell, but not strong. So I went to the pharmacy to get a Canesten treatment. It was ovules for 3 days and a cream for 7 days maximum. I finished the treatment on Sunday and 4 days later, I started to have brown/black discharge almost that I think is bleeding. Is this normal or should I be worried? I also feel like my lower abdomen hurts (slightly), as if I had my period but I had it 2 weeks ago. I'm not sure if it was a yeast infection, could it have been just an irritation and therefore made it worse with the pills? I have been on the birth control pill for 5 months now and have never had any bleeding between periods.