UPDATE: Back from the vet with Decker. Dr. H said his bladder was mostly empty so no blockage and that he thinks it's a severe UTI. He gave him an antibiotic injection and another injection to help with the cramping and discomfort. He said to try to keep him stress-free and to bring him back in a week for a checkup and another injection if needed.

I'll be keeping a close eye on him to makes sure the injections are working. He's very stressed right now because he isn't used to other people handling him. The vet tech remembered him from being that little wild kitten from under the deck. She was hugging on him and telling him how handsome he is. Decker looked absolutely terrified but took it very well thank goodness.