Hi Welcome to Healthcare Magic Forum Looks like your daughter has developed a lesion of Vector dermatitis or folliculitis. Vector (Paederus) dermatitis is a peculiar, irritant contact dermatitis characterized by a sudden onset of red lesions on exposed areas of the body. The disease is provoked by an insect belonging to the genus Paederus. Now firstly i would advise you to keep the area clean and dry as much as possible. Do not apply any kind of moisturizing creams/lotions or oil over the affected area. Wear cotton clothes so as to decrease the amount of sweating. Clean the area with lukewarm water twice a day and apply an antibiotic cream like mupirocin gel over the area twice daily. Give oral antihistamine like levocetrizine once a day to decrease the swelling If inspite of the above measures, the lesion persists or continues to increase in size, then your daughter might need a course of oral antibiotics along with pain killers..In that case, i would advise you to visit a dermatologist for proper assessment and treatment Hope it helps Wishing your daughter speedy recovery Dr Geetika Paul