hi and thanks for the query, a swelling, reddish and accompanied by fever is an indication of an acute inflammatory reaction. Considering absence of trauma, the most probable cause of this infection thus should be bacterial. Management shall involve use of antibiotics and analgesics. A good physical examination to visualize the surrounding structures and exclude any predisposing conditions, or associated lesions might be very helpful, Consultation of your primary care physician for broad spectrum and adapted antibiotics could be necessary. Exclusion of a possibility of pus collection could be helpful, in case incision and drainage is needed. Thanks and best regards, Luchuo, MD.