Allergies, hives, scabies and pityriasis rosea are few possibilities.
Red itchy bumps could be suggestive of allergic contact dermatitis.
Itchy red wheals which appear after food or drug allergy are hives. In scabies which is caused by parasitic infection the itching is common on hands, buttocks, back, genitals, and feet. The itching is worse at night. In Pityriasis rosea there is a single rash which spreads throughout the body in 7 to 14 days. A clinical examination is must for exact diagnosis.