What to do when you have a cough and....?

What should i do? I have a really bad cough and my mom thinks i am faking the whole thing just for attention...??? I am NOT faking it. i have been coughing constantly for about a week and she is pissed and telling me to stop because she thinks its just for attention?? what if its serious like bronchitis or something??? please help..this is a serious matter...