Hi , I Am 44yrs, BP Normal, Blood Sugar Normal,

Hi , I am 44yrs, BP normal, blood sugar normal, uric acid 5.7 .have been getting pain in knee's specially when climbing down stairs. No trouble in walking long distances. Some days it is more pronounced other times it is less. My ht in 5'7 wt in 76 kg. What diagnostic tests should I go for. Regards.