As Revauthi said it comes when he travels with crowd, So make him wear mask.

Sinusitis is horrible sometimes, I too have. Recently I started applying Patanjali 's Divya Dhara (suggested by one of my friend) and its very effective. Don't apply on his face but apply on his clothes and pillow.

Hi<br> It is important to treat colds and allergies quickly to avoid a secondary infection developing in the sinuses. Reduce nasal congestion by frequently using a nasal spray.<br> Use protection mask while traveling. <br> Drink plenty of extra fluids when you have cold.