Do Hormones Cause Heavy Blood Flow In The Morning In Women?

I had period problems so I visited a doctor.He did an ultra sound that showed nothing disturbing. He prescribed some pills which I have been taking for five days now.When I wake up in the morning the flow is still heavy but during the day after I have taken the pill the blood becomes less and at some point there are only spots. The doctor said that the problem is caused by hormones and he told me to do some blood tests. What do you think? Thank you for your time.