What Does Pain Only In One Leg And Ankle Indicate?

Went on a cruise last week for 7 days. Much more walking and step climbing than I do on a average daily basis. Starting about the second to third night after returning home I have been awakened by severe pain, right leg, pain centers just above the right ankle outside of leg almost up to the knee area. Not so much discomfort during the daytime hours but approximately after three- four hours of sleep after going to bed I am awakened by this pain and it continues the rest of the night. I am sure it has something to do with all the walking and extra climbing last week but wonder why I have only one ankle and leg that is giving me problems. Been using a lot of aleve, hot and cold compresses and last night rubbed some bio-freeze on this area. In FL until the end of March and not sure if I should go to a Walk-in clinic or hope it goes away on its own. Don't feel it is hugely serious but just don't know..Thank you...