if he's having multiple infections have him checked for sinus/nasal polyps...I had two back to back infections and my doctor sent me to have that checked out - I was the worst case my surgeon had seen.
I had them 'scraped' out (basically the sinuses are like thin walled grapes when you have allergies, repeated infections they stay swollen and you are sitting duck for any allergen, cold, infection, fungus etc) I was put under and only had some nose bleeding after the surgery. That was 2 years ago, no infections, no antibotics, no steriods, my snoring is gone and the headaches as well.
do some research on it but he sounds classic. Most people go the antiboitic or steriod route but I hate drugs personally.
Nasal irrigation is great it takes some getting used to but many cultures routinely clean the sinuses with salt water and I think the arruvedics (sp?) often use oils. If thats too much steam can help or encouraging the body to sweat/drip it out with really spicey hot until your nose drips foods...I find soup works wonders.