I have thought about this book every now and then and each time I try to look for it I'm unable to find it so if anyone can help that would be great! I briefly read sections of this book when I was like 11 or 12 and I was so scared that I never touched it again and I really regret not remembering it.

The main character in the book is a little boy that has a urinary incontinence issue and uses a sponge in his pants to hide it. But I'm pretty sure everyone at school knows and he gets bullied for it and I think his mom is pretty disappointed in him as well? And in the book he befriends a girl creature thing that can fly? I won't spoil any of the next parts unless it helps with finding the book, and everything I mentioned so far is revealed in the beginning.

Please help me find this book!! I don't remember the little boy's name or what era the book is in or a lot of the main plots but I'll try to think of more details if it helps!