6 week old has a bad cough ... Plz help ?

ok I took my baby to the pediatrician for being real congested and she prescribed him a nasal spray to break up the mucus. Well that's getting better, but now he has this horrible cough and I don't know what to do. Can I give him anything being 6 weeks old? I will take him back to the pediatricians if I have to on Monday, but tomorrow is Sunday and I was wondering if there's anything safe to give him for the cough until then or anything I can do? Thank you! Please help!