Hi, As mentioned by you that it started after a long walk. It is quite common to get muscle pain after undue exertion especially in old age. Since there was no direct trauma, I don t think there would be any major issue with legs and back however the long walk would have caused muscle spasm in your back area which would be the cause for backache and fatigue of muscles of legs would have caused pain in legs. There is no need to worry. I would advise you to take some common pain killers to get rid of the pain. You can also apply some local painkiller ointment for immediate relief. The pain will reduce and disappear gradually. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Anoop Kumar, General & Family Physician