Skye,
I probably woud be getting on the phone and getting someone to look after the girls.
Has Jesse been coughing previously to tonight?
The reason that he may bot be coughing now is that he is too tired to do so... Breathing fast will tire him out quickly and he might not have the energy to cought.
If you are still at home i would elevate his head so that he is not lying flat.
If he is awake i would try popping him on your knees belly down and firmly patting all over his chest, this will help break up the mucus so it is easier for him to get out.
How are his fluid levels? me more hydrated he is the looser and easier to bring up the mucus will be.
The vomiting Mucus bit has me worried, i would try and get him seen sooner rather than later

Hope he is Ok Hun