My 4 month old son having eczema on his face n gp gavel us zinc + castor oil cream n after applying that it gets worse?

Eczema treatment. There may be additives within the medicine your doc gave you that your son is sensitive to. Let your doctor know about the worsening of symptoms with the treatment, as many other options are certainly available. Also, make sure chemical free on clothing/bedding/burp rags - anything that could touch his face. No dryer sheets, use scent-free detergents and face washes. Finally, moisturize often.