Rashes - Dirt / Allergy / Insect bites or ?

My girl has stomach flu last week and doctor told us to let her be on soy milk for a week or till symptoms are gone. However, she starts to develop rashes this week (mainly on her hands). Is this due to dust, allergy to soy milk or other reasons? Any mummies have encounter these similar rashes before? #firstbaby #1stimemom