From the description you give and seeing the things that flare the lesions- it looks like Atopic Dermatitis
Its a form of allergy that manifests in the skin.
The skin usually will be dry and scaly in such infants. Changes in temperature, certain fabrics, cosmetics- like soap, baby lotions etc can cause flare ups.
You can have your child seen by a Pediatrician
or a Dermatologist
and get the diagnosis confirmed.
Atopic Dermatitis- is treated by keeping the skin moist with lotions like Cetaphil
, use of soft moisturizing soaps like cetaphil soap, use of anti-histamines if its very itchy.
In case the lesions are too much and not responding to above medications- your doctor will recommend mild steroid
creams for few days.
As your kid grows, she will gradually overcome the problem.
Hope my answer helps you.
Wish your little girl good health.