Aiyooo this sounds stressful lah, definitely kena check with your paed ASAP because those rashes could mean allergy or sensitivity to the formula, and they'll help you figure out which type suits her best (some babies need hydrolysed or lactose-free formula instead). A few of my mum friends went through this too and once they switched to the right formula, the rashes went away within a few days, so don't worry lah, very manageable once you find the right one for her!