I have for the past four night suffered severe pain behind my right knee feeling like cramp and upon arising and massaging the area, on the outer side of the back of my knee, the pain is subsiding. it actually wakes me, it is so severe, and feels like circulation problems. I have a fatty lump, which has been diagnosed by ultra sound, on the other side of the back of my right knee, which was checked on Thursday, but have had no results yet, and wonder if this could be causing the problem, or if I have a problem which needs to be seen by a doctor,I am very worried that it only occurs at night time at present . Can you give me any advice