From your description- it looks like your baby has atopic dermatitis
Its a form of allergy
that manifests in the skin.
Any allergen can cause flare ups. If the allergen is identified, its better to avoid exposure to them.
I guess the soy or cereal- might not be related to the problem.
too is not related to the problem.
You may visit your Pediatrician`s office and get the diagnosis confirmed.
Keep the skin moist. Avoid drying soaps. You may use moisturizing bars like cataphil/ oilatum. You may also apply cetaphil
moisturizing lotion after a bath.
For itching your doctor will recommend antihistamine syrups.
If the problem is severe- mild steroid
creams might be needed.
Hope my answer helps you.