Help😩

So 2 things I been having problems I have a almost 2 year old and 5 month baby recently my toddler had been throwing up her whole milk in curds whenever she gets it in the morning and poops real bad whenever she drinks it should I change milk or stop all together? 2 both my daughters has had this bad diaper rash for a few weeks now and it’s getting worse and I feel so bad I’ve used destin , a&d , Vaseline, and powder nothing Is working and they both are pooping like crazy should I just go to hospital?