Looks like you may need to do some trouble shooting,Check the tank behind the toilet to make sure the chain on the stopper is working fine and not getting caught on anything.Also check your water level, if you have a ball float there may be an adjustment screw or you can just bend the small metal rod[do it carefully as not to break anything].
I'm betting its coming from that end of your toilet, if the drain was partially plugged,it be overflowing or coming close.
