My Husband Strained His Calf Playing Tennis A Week Ago.

My husband strained his calf playing tennis a week ago. Pain, but no swelling. he played tennis again last night and had some pain and now tonight - a day later - his calf is swollen down to ankle an very noticable. Pain is moderate and uncomfortable but not like a broken leg and he can walk on it. Oh, and he's 51 and should stretch before going out for a tennis match!