“What causes these kind of wounds?”

My dad has deep wounds in his 2 legs and feet. He's not diabetic and it has been several months and he's still not healing, but now there's leakage from the leg. His pants became wet because of all the leakage and his legs became swollen. He wears tight socks since the doctor has him wear them to not get blog clots, but when he removes them his skin is peeling off. He can put pressure on his legs but it's painful. The doctor thought he had a bacterial infection but did blood work and didn't find anything. The doctor said in all his 73 years of being a doctor, a man this healthy getting wounds on his legs could only be from something he eats or drinks.