My 85 year old father has been complaining of pain at a small lump in his thigh for the last few days. Now he is experiencing more pain, from the knee, sharp and he has a knee replacement, and dull in the thigh. has trouble putting weight on leg and pain increases with weight and movement. Leg is stiff and he can't straighten it fully. He also says that he is feeling dizzy, light headed when standing, walking.