Mrs Ohio is a 52 year old lady with a history of Type I Diabetes Mellitus, previous myocardial infarction 3 years ago and Hypothyroidism. She presents with a 2 day history of right-sided leg pain and swelling. On examination, her right calf is swollen by 2.5cm more than the left calf and there is tenderness along the back of the calf.
Based on the likely diagnosis, what is the most appropriate initial management option?