Thank you for your question.
I am Dr. Su S. and I will try my best to help you.
As he is having fever
, fussiness, there can be an infection.
In infection jaundice can be increased.
He can need further blood tests like blood count, culture, liver function, ultrasound examination of abdomen.
Further tests will depend on finding of clinical examination & initial results of blood tests.
I hope this information will be helpful.
If you have any query, please feel free to ask.
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Wish his healthy life.