Right front brake is squeaking

I have a 2001 Z71 and today there is a grinding noise in the front of the car. The grinding started just today, there was nothing happening at all before this. I have looked under it thinking it might be the brakes but they seem to be ok. There is a lot of black/red greasy stuff but only on the right side. When stopping it sounds like an airplane is landing next me. It also constantly squeals. I also noticed that the brake peddle is going to the floor. I want to take it to have it looked at but I would like to have some input before I do. Does anyone have any ideas what it could be???

Get your truck to your mechanic ASAP b/c all that grinding is ruining your rotors your braking effectiveness is decreasing mile by mile. It sounds like the normal metal on metal you get when your pads have completely worn out. Don't delay, you might be able to just turn that rotor ($25) instead of replacing it ($100 in my town anyways)