Wow, so many ways to go here, all of which should be considered. The medical route should always be the first; make sure nothing is going on there. Next, I would consider the emotional route - has anything in your life changed recently? Have you moved, separated/divorced, are you pregnant or recently had a baby, did someone move in or out of your home, any kind of stressor (job loss, health issues, etc)? Some children are very sensitive to change and the smallest thing can have them set off balance and acting out. Another thing to think about although none of us really want to go there - is it possible he's been molested? Children who have been molested often exhibit bladder/bowel issues. Most likely, though, it's the "Hey, I'm a boy and I can pee anywhere and on anything" issue! My son went through a brief (thankfully) period of this when he was about four - peed in my flower pots, the tub, on the cat, etc. We solved it by talking with him about how it really wasn't okay to pee anywhere except in the toilet, then tried to make it fun by placing a bowl of cheerios in the bathroom so he could target practice as he went (made it clear they were only for target practice, not eating!). Good luck - I hope it's the latter and is over for you soon.
Liz
Liz