Help! Bleeding!

I had my period January 7th-12th. Totally normal, and on time. My periods never fluctuate, and are always the same. I obviously track them on here. I was given antibiotics and a cough medicine (both pills.) I started taking them around 4pm that day. Around 11:30 pm I started bleeding. It's now been 5 days and I'm still bleeding. Large clots and heavy bleeding. I called the doctor and he told me to stop taking the antibiotic and I should be fine, but also said the antibiotic shouldn't have made me bleed. 

Can anyone give me any input into why this is happening? Please & thank you!