Bleeding from uti?

So I just found out I have a uti (they told me it was severe) but I had no pain or symptoms. Now I'm on cephalexin 500 mg, 3 times a day. It is my third day taking the medication and I am now bleeding? I had my period about two weeks ago and I am supposed to be ovulating right now. Has anyone ever bled while taking this medication? I am going to call my doctor as well