I understand what you are trying to do but you haven't stated how you intend to sense the breathing.
Are you trying to measure the air movement or are you trying to measure the chest movement?
If you are trying to measure the air flow, I would use a "Hot Wire Anemometer".
If you are trying to measure the chest movement, I would use a strain gauge system. Either way you could easily make either system.
You could go to "Digikey" and look up strain gauge sensors and pick out one or two that would soot your needs. You would then incorporate the sensors into a strap wrapped around the chest
With respect to a Hot wire anemometer, I would make one using small gauge nichrome wire(26 or 28 ga). You would have to make four sensors with the same resistance and put them into a "Wheatstone Bridge". Two of the sensors would be in the air flow and two in the body of the sensor. The two elements in the air flow would be affected by the moving air and the two in the body of the sensor would account for ambient temperature changes. By the way, you don't have to heat the wires such that they are hot, just warm (100 degrees F or so).
As many commenters have mentioned, a piezo sensor is no really the best option. As far as using a microphone, most microphones are piezo-electric devises. Carbon mics vent out of favor many years ago.
With respect to voltage limiting, use a 5.1 volt zerner diode, tied to the Arduino's analog input. Hook the diodes cathode to the input and the anode to ground.
The zener diode will clamp the positive voltage to 5.1 volts and -0.6 volts in the negative direction.