2007 Mercury Milan Question: Why does my brake pedal travel so close to the floor before engaging the brakes?

My mechanic has checked the fluid, checked mechanicals at all for corners, checked the pads, bled the lines and found no leaks and nothing wrong. The brakes used to engage within an inch or so of applying my foot. A fe days ago, after I engaged the anti-lock brakes on a slippery road, the pedal got really long. I can barely fit my foot between the pedal and the floorboard. What is wrong?