I have had pain in both knees for about a week now. I can hardly stand to bend my knees..like when I sit down..they do hurt some even when I am standing or sitting, but not as bad as when i start to sit down. I have had 2 back surgeries..the last in 2004. I have gained about 30 pounds in the last year. I have never had knee problems, and am wondering if it could be coming from my back .