I forgot to add that I have had twitching in the left calf at times as well but it doesn't hurt, right now, it isn't happening, I have that sensation very seldom.
I have almost the same issue. I have pain behind my left knee but it hurts all the time but in different degrees. What walking, it feels like I am getting pinched very hard and it hurts, when sitting, it just hurts same as lying do0wn. If I flex my foot upward it really hurts for a while then the pain almost goes away. Also, if I get up after sitting for a long time, oh my, it hurts, its so stiff. I asked my chiropractor, he said I had tight muscles in my hip area causing this, but even when I do stretches it doesn't help, I guess I will have to see my GP as this has been going on for close to a year. I would say the pain fluctuates between a 2 to an 8
Oh, the chiropractor did say it could be a "Bakers Cyst" I looked it up, some of the symptoms are similar, it also said that it can go away on its on but takes awhile.