Does his urine look cloudy/dark or have a foul smell? Is he emptying completely or in tiny amounts?
Even though he's very young, there should be a pattern there, such as emptying
after naps, meals, water and playtime. What you have described makes me
worry a little about a possible UTI. I'd get him checked out, just to be safe,
especially if the answers to my previous questions are "yes, yes and tiny amounts".
Keep us posted!