3 days prior to operation, patient was prescribed with Clindamycin and Ciprofloxacin for Cellulitis and abscess on his left axilla. On his 3rd day of taking Clindamycin and Ciprofloxacin, patient experienced no relief and was referred to a GS and was advised to have it drained. yesterday px underwent drainage of the abscess as an out patient. One day after post-op, px complains that left upper arm is erythematous but experiences no tenderness and pain. Patient can freely move said arm. Patient doesn't complain of any allergic reaction/rashes to Celecoxib. What's the explanation for the redness?