as i understand it is often painful not always .
pain on movements mostly arises from joints .1 it can arise from hip joints because you say it is arising in upper leg or is it from knee itself . so to first rule out is osteoarthritis of hip joint or the knee joint .
2 then another kind of pain in old age is called vascular pain due to reduction in blood flow to limbs when walking and subsides fully on rest .
3 third kind is neurogenic where not just rest sitting or lying down may be required to get relief .
visit a orthopaedic surgeon and get evaluated for these

Hi there,
Thanks for writing in. I am a medical specialist with an additional degree in Cardiology. I read your mail with diligence. There are two differential diagnoses for such sever pain. Ischemic claudication and second is Nerve pain to dorsal and umbar vertebral spine disc or osteophytes pressing on Nerve. In atherosclerosis induced peripheral vascular disease (which is the commonest cause of ischemic claudication in later stages involves vessels supplying the nerve behave in the similar manner. Unless the disease is very progressed, the doctor after examination will decide, you ought to see the doctor on semi urgent basis. If not possible today, seek an appointment for tomorrow your doctor would examine you and order some basic tests like Limb artery Doppler and reach the conclusion which specialist is most appropriate for you. Please do not feel disheartened. My intuitive feeling is pain is definitively controllable and most of the limbs are salvageable. It is the nature of pain which makes one wince. Good luck

With Best Wishes
Dr Anil Grover,
Medical Specialist & Cardiologist
M.B.;B.S, M.D. (Internal Medicine) D.M.(Cardiology)
http://www/healthcaremagic.com/dr-anil-grover/63370