Since you just put on the new rest, make sure that your nock point isn't too low, it should be square to the string or just slightly high.

An easy, quick way to check is to get your drivers license or a credit card or something that has got a square corner on it. Nock an arrow and lay one edge of the card along the string, under the arrow, and the other edge should touch flush with no gaps at the front or back of the card. If the nock point is either too high or too low, it will be pretty easy to see and adjust accordingly.