Question about white cats...please help.

Spot got locked in the bathroom y'day while I was at work. When I got him out of there, there was a small spot on the floor that was reddish brown, I was afraid it was blood but after looking him over, I couldn't find anything.
His nose has been really red last night and today. His ears haven't been though. His nose wasn't cold but it wasn't hot either. I've tried watching how much is in the litter box to see if maybe he could have a UTI, but after having 2 cats before, I'm not sure if the little bit I'm scooping out is the "right" amount or what.
Am I just over-reacting or what? What do I need to be looking for?
Please help.

I'd have him checked for UTI - with males it's a matter of life and death. If they get blocked and cannot pee, they can die in a few days. To have peace of mind, call the vet and get him checked ASAP. Don't wait.

Thanks GoldenKitty! I rushed him to the vet and sure enough! What I had seen was bloody urine! He got an anti-inflammatory shot and some anitbiotics. He's not so happy with me right now, but he will thank me once he feels better.

Poor wittle Spotty! Tell meowmy that meowmaw said she better giive you lots of loving, cuddles and kisses tonight to help make you feel better!! Many that the meds work quickly!!