You first need a tetanus toxoid injection if you had not it in last six months. The insect bite has infected you leading to cellulitis. You also need an antiseptic dressing with a course of antibiotics with non steroidal anti inflamatory drugs. Visit your primary physician or the dermatologist who will do the needful. Leaving it uncared may aggrivate yor infection. If you are a diabetic please take full careof it.