What Causes Frequent Urination And Excessive Clotting With Bleeding?

Hi my name is Catherine Jackson and I am 18 years old. Yesterday i went to the doctors for bladder problems and they diagnosed me with UTI. As I was leaving the doctors office I had went to the bathroom and started to bleed. This is unusual because I am not suppose to get my period until around May 8th. All day yesterday and today, every time I have gone to the bathroom I have had excessive clotting or clots larger than a quarter. I have at least gone to the bathroom between yesterday around 3 p.m. to 4p.m. today, about 35 times. What concerns should I have.