D.M.
you need to take her to the doctor if you have not already,it is possible she is just a yucky stomache,but there is also something out there called the rotavirus not sure if I am spelling that right but it can cause diarrhea and vomiting my son had it when he was young and he could not keep anything in him. it lasted for about a week I believe. ask about giving baby pedialyte it puts electrolytes etc back into their body to help with dehydration not sure if baby is to young though or not. hope she gets better soon. hey and also if you can let the baby be free(might be hard with all the diarrhea going on)but if somehow she can air dry a little letting her behind be free along with the help of a good diaper rash medicine or vasoline it will give rash some time to breathe and out of the warmth.