Your wax gasket (seal) between the drain the the bottom of the toilet has failed and needs to be replaced. Very easy to do. I have done it myself. The only thing you need to buy is the wax ring which costs about $2 at the hardware store. Here is a video that shows you how -- this video shows you how to change the toilet bolts as well if it is needed:
No , not at all ! Sounds like you need to pull the toilet and put in a new wax gasket ! If you have tile floors , you'll need one gasket and a half gasket for a proper seal . It's not hard or expensive .