Blood in urine reoccuing UTI CT scan 3mm kidney stone bladder ultra sound scan shows bladder not emptying proper what could this be?

Cystitis. Gross hematuria probably as a result of cystitis caused by the bladder outlet narrowing or stenosis and not because of the kidney stone. By drinking more water like 8 cups a day you can pass the kidney stone. For the cystitis you need urine culture . Until the culture result comes back you can be put on an antibiotic such as cipro (ciprofloxacin) to stop the gross hematuria.