scared

So first night my baby has slept in her crib and she wakes up so I go to pick her up and I feel like her left side of her rib cage is poking out more than usual.. I thought maybe it was how she was laying but then even when I had her up right it sticks out more than the other ????? I'm a little scared. I don't know wha it is. She's laying down eating rn and I can see it sticking out now. I'm kind of scared, she's been very fussy but she's also teething 😔😔😔😔