General causes include:
Generalized pruritic papular eruption (PPE).
External parasites e.g scabies
Generalized fungal skin infections.
Generalized bacterial skin infection e.g., Impetigo
Exclude scabies, bacterial and fungal infections for which treatment is available.
Skin scraping for fungal element
Pus swab for culture and sensitivity
Treat the underlying cause
Treatment for PPE is generally unsatisfactory, but could be helped by use of antihistamine or appropriate antibiotics eg cloxacillin or erythromycin