Thank you for your query on Healthcare Magic.
His pale look may be due to anemia
Your child needs complete physical examination by a Pediatrician
to look for anemia,
signs of vitamin deficiencies, and for the examination of all systems.
He needs basic investigations like complete blood picture to look for the level of hemoglobin
ESR, chest X-ray, complete urine examination, and thyroid
Therefore I advise you to consult the Pediatrician for the examination and investigations for his paleness and weakness.
Hope I have answered your query.