sounds like there is a blockage usually a plunger will assist with this quite well. if this doesnt help you may need to call a plumber to have your closet rodded shouldnt be too expensive, but if he needs to rod out the drain and pull the toilet then that is more $$$
are you flushing anything your not supposd to? tampons, condoms,wrappers,tooth brushes?
when you flush it 2-3 times doesnt it overflow? or you wait for it to go down. Another thing you may want to try is cleaning the ring. get some rubber gloves(your chioce) and a coat hanger..use the end of the hanger to poke in the little holes under the ring.. be sure to go all the way around the ring and clean them out good. especially if you have hard water.