My hubsand squated down to day to pick up a small item, when he raised up he heard a pop and was in severe pain/ could barely walk. This was around 9:00 a.m. at 3:00p.pm he went to the doctor, from his knee down was swollen he was given naproyxen, as he was leaving we saw that the back of his leg had a huge lump where the leg bends this was not there before. The m.d. said he has no clue what it is does anyone have any idea? His leg does not really hurt to walk on now but it is really swollen. He has appointment with a orthopedic surgeon/doctor tomorrow. Oh a couple of months ago he injured his other knee and wore a knee brace and took naproxen for it.