Check the seal between the tank and the toilet.tighten it as necessary. (not to tight! you will crack the ceramic). Mkae sure the tank is square to the toilet.
also the water inlet connector.

This is a most likely caused by the toilet not being mounted properly. First, turn off the water supply. Next flush the toilet. Then, take a shop vac and remove excess water from both tank and bowl. Once that is done, disconnect tat supply line going to the toilet. Disconnect where the supply line connects to the tank. Finally, take the nuts off of the Johnny bolts. These are the bolts that hold the bowl to the floor.

Then remove the toilet and scrape off the excess wax from both the bottom of the tank and also the flange on the floor. Next, you'll need a new wax rings and possibly some new Johnny bolts. These can be bought at a local hardware store for under $10 total. Sometimes you'll need to put the new Johnny bolts in because when the last ones were cut off to get the egg caps on, the threading would get screwed up.

Now, take the wax ring out, place it over the flange so you can see down the sewer pipe. Put the new Johnny bolts in on each side of the flange. Center them so that they'll line up with the holes in the toilet bowl. Lift the toilet up, and set it down squarely on the flange, making sure that the Johnny bolts went through properly. Sit down and rock the toilet down on the wax ring til the wax has done its job and the toilet sits firm. Put the washers over the Johnny bolts, with the lip up so that the egg caps pop on when you're done. Next, put the metal washers down over the Johnny bolts. Then screw the nuts on until it's firmly in place. Don't screw too tight or you'll break the bowl. Now, take a Sawz-all or just a hacksaw blad and chop the Johnny bolts off so that you can put the egg caps on. Then hook up the supply line, and turn the water back on. This should fix your problem.