When you warm up, start out by doing them softly and with no strain at all. Warm ups are not designed to be workouts.. When you go jogging, you stretch first. Like any physical activity, warming up just makes things go easier. Working out, on the other hand, can be strenuous. Try doing some easy warm ups just loud enough to not be airy. My $.02
Also, awesome cover dude! Where did you learn orrendo canto? as far as I can tell, there are no orrendo canto teachers in the states where I live.