Has been having vs has had

A carer's leave or the carer's leave?

JigneshbharatiMy son has been having high temperature since Friday.My son has had the high temperature since Friday.Could someone please explain to me the difference in the meaning and which one is correct to use?

They are synonymous and both are wrong. These are correct:

My son has had a high temperature since Friday.
My son

JigneshbharatiA carer's leave or the carer's leave?

I'm not sure what either one means.

A medical term for above-normal temperature is fever.
My son has had a (high) fever since Friday.
My son has been running a (low-grade) fever since Friday.

Instructions for my son's caregiver / baby sitter / au pair.

Thank you all. Why do we use "a" highly temperature and not "the" high temperature? Can we use "having" in "he has been having a fever since Friday"?.
A carer's leave( emergency leave to look after my son because he was poorly) or "the" carer's leave? Basically it's a type of leave, you need to select as an option.
I just want to know the " had been having" construction.

JigneshbharatiWhy do we use "a" high temperature and not "the" high temperature?

Because it is not a specific measurement.
"A high temperature" is some measured value over 100° F.

JigneshbharatiCan we use "having" in "he has been having a fever since Friday"?

No. "Have" is not used in the progressive form when i

JigneshbharatiCan we use "having" in "he has been having a fever since Friday"?.

No. This is one the distinctive features of Indian English in particular.

AlpheccaStars"Carer" is not a good word in American English.

It's used in the UK http://dictionary.cambridge.org/dictionary/english/carer

I am just confused about the use of "a" in front of "high temperature". Is temperature uncountable here and what about "high"?

Why can't we use "having" in the given context?