My brakes on 99.5 A4 have been acting weird. when i brake, if I really step on the brakes hard, it does a noise. well, that was before. Last time I drove it, I braked normal like 35 mph to a regular stop and felt the pedal going further inside and not braking. And little by little it started to go further inside and not braking.
Brake pads are 20% used, brake solution is good.

What is my problem?
Thanks a lot.