Congested at 6 weeks

my son is 6 weeks old as of yesterday and he’s so congested I can hear the mucus rattle in his throat when he cries. The doctor said saline drops and the humidifier, but my little one gets to crying and is practically inconsolable and has been crying all day for the past two days. I went back to work today and my poor fiancé was at home alone in the front line. He’s even been refusing to sleep on his back at night and will only sleep on my chest. I read an amazon review a woman used this on her baby at 6 weeks even though the packaging says 2+ months. Has anyone used this or have any advice. I thought about putting little dabs on his feet and putting socks on to see if it helps him at all.