poop up her back

Cara
So the past few days while my daughter is napping, she poops. The second she wakes, she automatically sits up now. With that - the poop seems to squeeze out of the diaper and up her back. 
She is in pampers swaddlers, size 4. She is 27" and almost 19lbs. So she is kind of already up a size already. 
She is sitting and army crawling. 
Would cruisers help?
HELP!