@jcboy,
Best to keep him home as the first days are when colds are catching..
plus the comfort is good. A lot of us have memories. I think I remember a mustard plaster (what?). I remember not chicken soup but milk toast.
I suppose milk toast is out by now (mucous activating?) but it was comfort food.
Sore throat and not sniffles? sweating thus fever? watch his temp. Watch for rash.
On the don't worry side, most of my early colds started with a mild sore throat.
On the worry side -
I never had strep throat by itself, but I did catch scarlet fever, which is caused by streptococcus, and can be serioso.