What Is The Treatment For Severe Thigh Pain?

I developed pains in my thighs during a two week vacation early in December 2010 where I did a lot of stair climbing...With rest I feel much better now...Are there any excercises that I can do to make my thigh muscles strong enough so I can take another two week vacation in April 2011 and climb stairs at tourist sights ? ...I am a 82 year old male 5 feet 7 inches tall and weigh 160 pounds....I usually take a two mile walk on a level plain each morning with no leg pains...However, those stair climbing events of a couple of weeks ago sure did leave me with thigh pains that I even had difficulty getting up out of a chair...Please help...Charles Neugebauer