Bumps, itching, redness and other skin conditions are the forms of skin allergy, inflammation of the skin. Skin allergies are caused by a wide range of allergens, including foods medication, cosmetics, and clothes.
Signs of life-threatening skin allergy 
Swelling of tongue and/or throat
Difficulty in swallowing or speaking Vocal changes (hoarse voice)
Stomach cramps or vomiting
Dizziness, loss of consciousness, floppiness (in babies)
When to seek
Most skin allergic reactions don't require medical attention. See your doctor if symptoms persist or worsen as the allergic reaction may be more than just a rash.