Brake Disc Pads problems of the 2017 Chevrolet Camaro

While driving on the highway at 60 -70 mph in light to medium rain and it was around 35 degress, my brakes failed to work. I pressed on the brake pedal and there was no resistance. The pedal went to the floor and no brakes were applied until 3 sec. It felt like it was building pressure and after 3sec it applied the brakes forcebly becuse the petal was on the floor. It was very scary and I almost got into several accidents. The problem kept occuring during the entire 3 hr drive. Everytime I wanted to use the brakes I had none unti after 3sec. The car has 25000 miles and still the factory tires. Around 4months ago I had the rotors and pads changed out by the dealer. After I reached my destination my check engine light came on. Not sure if its related or aother new issue. Car has been at the dealer for 3days now.