The water could be coming from one of five areas.......
1) the toilet flange (not sealed properly between the gasket and toilet flange)
2) the gasket between the tank and the bowl isnt seated properly
3) the overflow tube inside the tank...........if the overflow tube in the tank is not seated properly, water will splash against the back of the inside of the tank and make its way down the back of the tank and before you know it, there's water on yer floor.
4) a hair line crack (yep, i just said crack in a plumbing question) in either the tank or the bowl
5) the kid is pissing all over the floor
Once you figure out which one is the problem, then you'll have it licked.
That'll be $50 please.