2494. The most loved cat in the block has difficulty peeing

Previously able to run down 16 floors and climb up 16 floors after going outdoors. Last 2 months, would wait for the owner to come to look for her, maybe at the 3rd floor.
"Why would a cat climb up and down 16 floors of the apartment?" I was surprised.  The slim lady owner in her late 50s do that. That was why.

Today, Jul 14, 2015, her busy son took her and the cat to me for treatment. The cat could not pee on the litter box, just squatting but could pee on the bed and blankets when lying down.

What was the problem?

1. Everybody loves this cat as he meows when fed and meows to "thank" the giver after eating. "Other cats would just eat and go silently," the woman had never stayed apart from this cat.

2. "This cat has a good memory of going to the vets," she told me. "He would avoid getting into the car."