65 year old male - swelling in feet and ankles recently started 10 mg of cyclobenzaprine 3x daily

Many possibilities: Some causes of swelling of the feet and legs can include systemic problems such as hypertension, and problems with the kidneys and localized issues such as arthritis, cellulitis, lymphatic obstruction, blood clots, varicose veins, trauma and side effects to medication. Have it evaluated by a professional and get the appropriate treatment.