Standing on my right knee causes pain that of burning sensation. it lasts secs once i get off knee. no swelling. fallen on them 10yrs. nerve damage?

Sounds like you have: Arthritis, or a meniscal tear. The fall might be responsible for the arthritis, but i think its the daily activities with subtle injuries in a susceptible person resulting in a meniscal tear. Its not a nerve issue. See an orthopod and I am sure he'll help you. In the meantime, use a cane for support, as I have seen too many people falling ; making it worse. Good luck.