I would set up HEALTH global variable and when HEALTH = 2, show Frame 1, HEALTH = 1, show Frame 2, HEALTH = 0, show Frame 3 etc. This way you can subtract values from HEALTH when an enemy hits the player so it updates.
To keep the health on screen scrolling with the player you need to put it on it's own layer and set the Parallax to 0,0 (under layer properties).