7mth old baby not eating, diarrhoea, very unsettled his eczema has flared up and has white sort of bumps on the inside of his cheeks (mouth)?

Dehydration?: Infants can easily become dehydrated, especially if they are not eating and having diarrhea. This can happen quickly, can be very concerning, and warrants a visit to the doctor. Viruses are common in this age group and can cause decreased oral intake, diarrhea and oral sores (among many other symptoms). Fungal infections (candida/oral thrush) can present with white patches on buccal mucosa.