Is the mucus clear/white or is it yellow/green? Clear/white means no infection but yellow/green means there is an infection. Is it possible he could have allergies, as in airborne?
If it is a common cold then it can take up to 14 days to recover from it. We always use the theory "10 days coming, 10 days here, 10 days leaving" ; seems like a long time but sometimes you aren't really aware of the first 10 days. I never used decongestants but then my guys refused to take most medicines.
Well-behaved women seldom make history!