Have you seen water around the base of toilet? Is the vinyl flooring have stains bleeding through? Does the flooring feel soft or spongy around the toilet bowl?
I look at a lot of toilets, and it is amazing how many of them leak. Often these leaks are very small, but over time can cause a lot of damage.
Here is a video on how to reset a toilet, it is not too hard the parts are cheap. There are some important tips you should know before you try this for yourself.