4 month old with a cold

Please help.. I’ve done it all. Saline drops, bulb suction, hot shower in the bathroom, vapor baby wash, cold humidifier, zarabees cough & mucus.. idk what else to do. He’s so miserable, he won’t lay down by himself so I’m holding him. I know it’s because the mucus goes to the back of his throat and down his nose so he can’t breathe. It’s making me so sad… 😞 if anyone has any other tips please please comment!! He has his 4 month checkup on Tuesday but I’ll call and move it up to tomorrow if I have to!