Dear sir,
Nothing to worry with chicken pox.
Give fresh oxygen and make sure that his surroundings should be very Hygienic.
Next Steps
Use Ayurvedic medicines like Shadanga paneeyam, Useerasavam .
Once in a life time it will effect,Use buttermilk with little bit salt added
Health Tips
The pigmented patches will soon reduces maintain hygiene n be patience for 7-10 days monitor the patient giving him support to recover.