EM@3AM: Cellulitis

A 56-year-old male with a history of type 2 diabetes presents to the ED with a rash on his right shin that started two days ago and has progressively worsened. He has associated mild pain but has not taken any analgesics.
Vital signs include HR 90 bpm, BP 148/100, RR 16, T 100.2F, and SPO2 96%. Examination is significant for an obese disheveled male in no acute distress. His right shin has a large area of erythema with indistinct margins and increased warmth, as well as associated mild tenderness to palpation. What is the most likely diagnosis?