My Grandmother Has A Wound Like Thing On The Backside Of Her Leg Alomst On The Ankle. What to do?

We Have Seen Doctors From Most Of The Departments And None Of Them Have Been Able To Find Out The Cause. Where Do I Look For The Solution? The size of the wound seems to increase. She has difficulty in walking and the foot is swollen. Its been 5 months and still she is in pain. Please help. It seems like the skin is melting or something.