What Causes Pain In The Inner Thigh And Knee?

Hi I have had pain in my inner thigh right down to my knee since last friday, it seems to start at the groin. Now the pain is travelling to below my knee. It is very painful to touch and i cannot put any weight on my knee. Hospital have checked for DVT and infection but blood tests came back all clear. I also have a swollen lymph node in my groin, no symptons on the surface - seems to be tender to touch more internal than external