Injured Pitcher

[rj]

This is a High School Game:
Coach calls time and replaces his starting pitcher because she has a sore shoulder. He asks that because he's replacing his pitcher due to injury his replacement pitcher get as many warm-up pitches as needed; which is granted.
He immediately sends his starting pitcher to center field as a substitute for his center fielder. Is this legal? Does the injured pitcher have to leave the game? If she doesn't have to leave the game, does the replacement pitcher still get as many warm-up pitches as need or does she only get five?