My left knew at times does not seem to want to bend. It feels as if something is stopping it. Have trouble walking and going up stairs. Have had x-rays, bone scan and MRI and nothing shows up. However on MRI of lower back I have a slight herniated disk. My leg seems to be slightly swollen can feel the difference when wearing pants. What can it be? Any ideas.

I also have a pain in my left side of my nect could this have someting to do with it? Never been checked for herniated disk in that area.