Knee stiffness

Any ideas would be helpful. At rest knee is fine. After sitting car home etc. When I first stand and walk there is some pain and stiffness in knee. After walking a short distance it gradually gets better. Less pain and stiffness to the point where its 90% normal. I had it i my left knee for a couple of days and it totally went away. Nows its in my right. I have noticed if I kneel the next day it will be sore. Dont know if the two are related but it seems like the are.
Thanks