Hello,
you cat needs to be seen by a veterinarian ASAP! The big concern is that the blood in the urine will cause a blockage in the bladder and inhibit the ability to pass urine.. which could be deadly. Please call your vet now and ask for help. ideally these cats are examined, hydrated, and given something to help with pain, infection (if needed) and monitored very very closely so that they dont block. Also it is imperative to discuss why this might have happened and address that so it doesnt keep happening