I am not sure he has a infection as a root cause. Sounds more like allergies that irritate until an infection begins.
The honey should sooth as well as being a mild antibacterial, the smoothie and extra sleep should help build him up, the neti pot should help with the drainage that seems to be happening.
If that helps but does not end the problem then he should try one drop of oil of oregano in a cup of warm water.
On the other hand if his fever spikes to over four degrees above his normal then forget the self treatment, he should head for the doctor asap.
Excellent suggestions.