You seem to have developed an infective lesion after the insect bite.
You need to keep the infected area clean and dry.
Use a topical antiseptic lotion for cleaning it.
You can also use lukewarm saline water for the same.
Apply a topical antibiotic
cream over the area twice a day.
You might need a course of oral antibiotics
if topical local treatment alone does not suffice.
Dr Geetika Paul