I'm mad at my parents for not taking me to the doctor
Why does this make you mad? Did they tell you why they don't want to take you?
I'm mad and I don't know what's going on
Parents should be looking after their children, and getting them the proper care when they are sick.  However, if your parents did not take you to the doctor, they may think that you just need to rest and recover on your own.  See if you feel better tomorrow, and then talk to them about it.
I don't know why you wanted to tell me that
It's a parent's job to take a sick kid to the doctor. But if they are not taking you, they probably just don't think that your sickness is very serious. You should talk to them, and they should explain their reasoning to you so you don't worry unnecessarily.