Tips to make going to the doctor less painless?

I have a doctors appointment tommorow and for a lung inflammation problem and i dont wnat him to just perscribe me meds and send me on my way i want to know the cause of this. I love my doctor hes the best but for some reason whenever it comes to the asking questions part i always freeze up and dont say anything, then i kick myself later for it. Any tips on being more confident at the doctors?