Red blood cells in urine after having antibiotics for uti

Hello I am 30+5 over a week ago I got a phone call to say there was red blood cells in my urine sample they usually allow 10 as normal and I had 110 so they believed I have a uti and gave me antibiotics, I then had another sample taken yesterday and they have said there is still signs of red blood cells so sending off for results. What else could be the cause? As i have no pain or symptoms of a uti. Anything will help.