Thanks for the query,
Probably he has developed chicken pox
It is better to avoid day care till the time the rashes dry up.
Please apply an antibacterial cream on the rashes.
This will prevent secondary bacterial infection.
Also give him an antihistamine syrup.
This will give him some relief.
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.