Looking very strange.
His left eye is showing signs of redness currently. It's very watery and he seems to be having trouble keeping it open. There's no discharge except the wateriness.
As for his belly, there is a spot on it. Circular and pinkish-red. It looks dry and agitated.
He is not an outdoor cat. He has no fleas and had no ability to get into anything outside. (He's honestly terrified to go outside.) He's not around other cats either.
So far I've been cleaning his eye with a warm cloth. Should I put a little salt on the cloth? He drinks plenty of water and he doesn't appear to be having difficulty rating or being playful. He sleeps most of the day and is active at night. And he's been pooping and peeing regularly, too.
Here is a picture of his belly: