There Was an Old Lady Who Swallowed Fly Guy by Tedd Arnold

A play on the similarly titled song, this is one of a series of Fly Guy books.  In this book, fly guy gets swallowed, and yet is still able to save the "old lady" from impending death with the help of his friend Buzz.

More Parts by Tedd Arnold

A boy is struggling to hold himself together as he learns that his heart is breaking, he can give someone his hand, he can crack up, hold his tongue (and possibly drop it) and more.  Finally, his parents help calm him down and explain things.  And everything is find until he finds out he can lose his mind.