Re: having HUGEEEEE problems with 3 yr old peeing!
ok 2 possibilities--
i'm a nanny, so that's how i know these things, btw...not a parent yet--
1. if he has a uti, they'll avoid the bathroom, hold it in, b/c they assoc the bathroom w/ the pain of peeing-- then event they lose control. if he's crying when he pees, this is likely the case. esp if he's been going swimming lately, can cause uti's
2. sometimes children, esp around 5-6, will go thru a phase when they just hold it in a lot and have accidents b/c they're just so busy having fun and doing stuff, and this will usually start at a time in their life when a new activity starts--like you get a new trampoline in the backyard, and the same day your 5 year old wets his pants for the first time in forever. b/c no way was he going to take a break, just kept putting it off. but this usually won't happen repeatedly in one day.
these bathroom prob's usually aren't psychological, usually either physical, or just a behavioral issue of some sort---anyhow good luck.