I have studied your case.
Most common cause of knee pain
. I will advise you if possible do X ray
of knee and you can consult me with reports or with your doctor.
Another possibility of leg pain is due to burgers disease which is common in smokers.There is occlusion of lower limb blood vessels and leads to burning pain in lower limb.
I will advise to do colour doppler leg.
Hope this answers your query. If you have additional questions or follow up queries then please do not hesitate in writing to us. I will be happy to answer your queries.
Wishing you good health.