Sorry to hear that news,Skieslimit.
Is the tonsilitis/runny nose made worse by food allergies?
High factor Manuka honey,given about half hour away from food&drink is amazing to soothe throat problems.
Also some fuchsia(juice from the flower)for throat.
Vit C
echinacea,
black elderberry extract is also a great immune booster but I don't know any brands that don't have some kind of sweetener anymore.
Sorry may not be really helpful,just wanted to contribute here,
I hope he's feeling better.