need help !

went to the doctors becouse i had a uti took antibiotics and it cane bak again but worse with bloood went bak to doctors they then gave me another set of antibiotics and now i think it may of come bak again has its burning slightley when i wee and im haveing bad stomoch pains on the top left but about a week ago i had to swnd a urine sample to the lab and it has come bak clear what could this b has this is the third time now