Am I invisible?

I swear to God-nobody listens to me? Do you feel like your parents/in-laws don't hear a word you say? For about a year now my daughter pukes when she cries/gets upset-see earlier post. I have explained this to my in-laws a number of times. 

While she was over there today, they put her down for a nap and after an hour she woke up crying. And-you guessed it-she cried so hard that she vomited! My mother-in-law calls me to tell me this concerned that she might have the stomach flu. Can you believe that? I even said to her that nobody listens to me. I have told them so many times that she pukes cause she's upset. But she does not understand why that would happen so she doesn't believe me I guess. She is the kind of person that needs to understand in her own way why a thing happens and not the actual reason. She has asthma so this is something that comes along with it.