When your toilet tank is not secure you could develop a leak. This guide is about toilet tank wobbles.
We installed a new toilet and something doesn't seem right. My husband said he tightened the bolts that hold the tank onto the bowl, but it wobbles as if they are extremely loose. I was very worried about this, so he put a small piece of 2 X 2 between the tank and the wall. Now there is no wobble, the tank is level, flushes right and doesn't leak, but I'm still worried. Anyone have any ideas?
You might want to check the toliet flange under the toliet meaning where the pipe and the toliet meet, you might need a new wax ring or your floor from the leaking might be rotting out your floor, I found this out the hard way myself. I would suggest taking the toliet out and check what you have going on there, mine rotted out the whole floor around the hole, not a good situation.
The answer is called a plumber.
Go to store and get a tube of stuff to put around the bottom of bowl where it meets the floor. I forgot what it is called. I think it comes in powder form too, it's not plaster of paris but sort of like that. It dries hard and is waterproof and will support of whole thing.
Ask for help at the store
Instead of a piece of wood use a toilet tank stabilizer by Tank truss. This is adjustable and can easily be put on most toilets I've installed. This will stop the wobble and movement in the toilet tank. http://tanktruss.com They can be found at Ace Hardware stores.