Baby health

I’m worried my 3 month old has pertussis or something wrong with him. I made a doctors appointment but it’s not until tomorrow morning. He has this cough that started out dry. Now it’s a little wet and he sounds congested. He coughs a couple times and then grunts when he’s done. I received the tdap vaccine while pregnant and he’s also received his first round of shots at 2 months. I’m trying to get a video of him coughing so I can take it to the doctors with us in case he doesn’t cough for them. How do I go about telling the ped that I want him checked for pertussis? I don’t want them to think I’m paranoid I just want my baby taken care of. Like this morning I laid him in his bed, he started crying and coughing. I’m really concerned.