I was waiting for your reply.
Without further information from you, I am writing the answer.
There is likely to be an infection in the throat.
Viral or bacterial infection can be there.
In high fever, there can be vomiting.
Infection can also cause it.
In case of frequent vomiting he can develop dehydration.
Please watch his urine output.
In dehydration it can decrease.
He needs an examination by doctor.
He can need a few tests like throat swab, blood count.
Please try to give oral rehydration solution like pedialyte, equalyte in sips.
In this way he can tolerate fluid & prevent dehydration.
Tylenol can be given for fever.
If you have any further query, please feel free to ask.