having pain behind both knees I asumed I might be getting varacose veins. My primary says no, but suspects I have Artritis in both knees. X-Ray tomorrow, awaiting insurance pre-cert for MRI. Well, since yesterday, the left knee has been having constant sharp, shooting, extremely painful "stab" like feelings now come from the front. Walking, sitting ,doesn't matter. More than ever though when I stand the pain (pain, but not quite a "stab") really comes stronger from behind my knee. The last 2 days it seems it's gotten worse. I'm 46, active and concerned about what is happening. I really don't know anythng about joint health and would appreciate any feedback. Thank yo for your time.Carolyn