Almost 4 yo old started having several accidents a day again. i don't think it's uti as he goes a lot when he does go and he doesn't do it at day care?

Check Blood Sugar: If you have a four year old who was formerly potty trained for day and night, who is now having daytime "enuresis" ( accidents) especially as it seems the volume is ' a lot" he needs to be seen by a physician for an evaluation. If you have any trouble getting him in, check his blood sugar with a monitor you can buy at Walmart. It should be less than 100. Diabetes can present exactly this way.