Thank you for your query.
The itchy rash is looking like an allergic rash
It is not looking like due to scabies
or hand foot mouth disease as there are no papular or vesicular lesions and there is no oral involvement.
Allergy may be due to food or bedding clothes or due to any exposure to allergen.
Kindly observe to find out any allergen.
lotion for external application.
Consult your Pediatrician
for examination and for the prescription of oral antihistamines for itching.
Hope I have answered your query.