Welcome to Health care Magic.
Based on the details given by you, your brother is obese
. He needs to lose atleast 25 kgs of weight. Coming to the skin infections on his legs. He could well be suffering from Diabetes
. As he is obese there is every chance of him being diabetic and moreover obese and diabetic people are prone for a condition called Necrobiosis Lipoidica( Due to Necrosis
Please get the following tests done
CBP with ESR
Fasting and Post Lunch Blood Sugar
These are the basic tests required. If these test turn out to be normal only then you can investigate further.
Please repost with the reports of the above tests so that i can guide you.
Have a healthy day
Bye & Take Care