Please help 😕

My baby is 3 weeks old and has been breastfed since the beginning . Sometimes breast sometimes bottle. I’m really struggling with her diaper changes. I’m not sure if this is normal breastfed newborn poop. Her poop is yellow and does have some seedy parts but for the most part it’s straight liquid. My husband and I can’t even change her diaper without going through 4 diapers first. If she sneezes she shoot’s liquid poop out and if you lift her legs she projectile poops . It’s honestly an anxiety trying to change her. On top of that she has had an awful diaper rash for two weeks. Open sores . We have tried everything. Our pediatrician was not much help at all. She suggested maybe cutting dairy out of my diet to see if it helps at all. I’m just wondering if anyone else’s baby has super watery poops or how to fix this diaper rash. We keep changing her and do diaper free time. We have used triple past and a ton of other creams as well. It was getting better then it went back to getting red again and new sores forming. I really want to breastfeed my daughter especially since with my first I had to exclusively pump and this is our last baby. I’m feeling so defeated and thinking of switching to formula to see if makes her poop less or helps with diaper rash.