Nearly 3 week old cant poop

My 2 week 5 day old seems to not be able to poop today. She usually poops every day, she has had like sharts in her diaper today but no full poop. her stomach gets big and I can literally hear it rumbling and she cries and kicks and it makes me so sad that I cry that she’s in pain maybe. Is there anything I can do? Preferably natural