Upper chest bite with 4 inch reddened, raised inflamed area with temp of 100.5. benadryl 50 mg taken a few hours ago. have not taken tylenol (acetaminophen)?

Inflammation and: heat usually equal infection. In this case it is very likely that you have a secondary bacterial infection from the bite. Hypersensitivity/ allergic reaction can also cause inflammation and heat but the infection requires a thorough examination by a trained clinician in order to diagnose and provide appropriate treatment. Please see a healthcare provider soon.