Help pls. Newborn problems!!

Letty

So I’m breastfeeding pumping n giving my bby my breastmilk in bottle for the most part .. but I feel like she poops so much like every feeding. She poops or squirts. When I’m feeding her, Or when she cries she squirts a bit so I’m constantly changing her diaper. Also she has a rash on her butt bad bc she poops so much.. how can I get rid of her rash. N why she poops so much is it Diarrhea or is my breastmilk I’m trying formula Mayb that will help her from pooping so much. Am I doing something wrong. Is it my breastmilk .. is it diapers? Wipes? I need. Help. My poor bby I hate rashes!! N 2mrw she’s seeing her doc .. I’m just worry about her rash!