Breath by Donna Jo Napoli

Breath occurs during medieval times and is a great book to read even if the cover looks pretty scary and groosome. It's about a farmer boy named Salz who is "salty" or sick. He can't breath well because of his sickness and when he starts to cough he has to throw himself into a handstand to fight the cough. He doesn't drink ale (beer) like everyone else because of his sickness and is an outcast. During the summer something seems to be afflicting the livestock of Hameln, the town where Salz lives. Pretty soon parts of the animals turn black and fall of and they start to die. Then people start to act mad starting with the townsfolk. Soon the people die like the animals and they blame the rats for the disease. Salz is tried for the cause of the disease since he's sick after his grandmother was murdered. He's set free of the charges and tells of a piper he meet when he was in the woods who could free Hameln of its rats. The piper comes and frees the town but when he doesn't get paid what he was promised he starts to play his "people" music and makes the people follow him out of town but the sick and lame are sent behind. That only leaves Salz and all of the healthy children to follow the piper. It's time to pay the piper.