I have a toilet that rocks and by the time I go down stairs and get my tools and come back it is secured to the floor and won't move. I have lifted the toilet up and put a new wax ring in and tried a couple of sims but after a few days it starts all over again.How can a toilet be secure then rock and then secure again without touching it.The tolet flushes great and there are no leaks or strange water noises.It's driving me crazy, HELP

I have a toilet that rocks and by the time I go down stairs and get my tools and come back it is secured to the floor and won't move. I have lifted the toilet up and put a new wax ring in and tried a couple of sims but after a few days it starts all over again.How can a toilet be secure then rock and then secure again without touching it.The tolet flushes great and there are no leaks or strange water noises.It's driving me crazy, HELP

Rotten sub flooring needs replaced. Its spongy, but not rotten mush yet.

Very strange phenomenon indeed.

Two things happen when you flush. One the water in the bowl goes down the drain. Second the tank is emptied and refilled.
Try turn off the water to the tank and flush to see if the refilling of the tank has any effect.