I have been to doctors and they say these no infection currently but my urine contains blood and it burns after i urinate?

Doctor can follow up: A urinary bladder infection is a type of urinary tract infection. Bladder infections are usually caused by bacteria making their way up the urethra into the bladder. A doctor's evaluation and a urine test are usually needed to decide what the problem is. Also, there are other causes of blood in the urine, such as kidney disease, non-infectious cystitis, cancer, etc...