What Causes Skin Disease On The Lower Part Of Both Legs?

I am a 28 year old male with a skin disease on the lower part of both legs. one of the doctors told me that it is a kind of eczema and have given ointments and tablets for it. But there is no effect and i am not sure it is eczema or not. what is the best way to find the exact disease. is biopsy useful , if then where i could go and check. i live in kottayam district