In riviera maya mexico i cut my calf on some sharp organisims (barnacles?) on the side of a buoy. hurts to walk on, and ankle swollen. what to do?

Go to resort doctor: Most larger resorts have some medical care available and you should seek medical attention to get appropriate oral antibiotics treatment if needed.

Get to a doctor: It sounds as though the cut may have become infected. See a doctor for an evaluation and see if antibiotics are indicated. Infections can get worse fast, so don't wait too long.