Thank you for your query.
It is very common for children of this age to contract infection quite frequently as they are building their immunity. If the investigations are normal and the growth of your cousin is normal then you need not worry. Some children with upper respiratory tract
infection tend to vomit more in the initial period due to a congested throat.
I hope I have answered your query to your satisfaction.
Wishing your cousin an early recovery.
Rajiv K Khandelwal