Could Demise In An Infant Be Due To Dehydration And Vomiting?

I took my 13 month old to the emergency room we explained the symtoms she looked dehydrated and vomited twice with diarrhea and a rash with purple red colors that faded at times, the doctor did not took it serious and said to me why you bring her in for is that medical negligence ? I TOOK him 5 hours later with the IV on her to take a chest x-ray. When we arrived to the second hospital it was too late her sugar was low and needed oxygen all we kept hearing was that she was very sick, in only hours my baby passed away. was blood transfusion really necessary ? she went triple her size with al the atibiotics on her. I left that hospital knowing they didn t even knew what they were doing to her. plus the first Dr. did say she looked ok to him really?? at the childrens hospital ( the second h ospital) they gave us like five types of diseases she could have but they were sure they did not know what was wrong with her.