You can always ask for a second opinion, has he done that? I know doctors can be very very up their own arses but they should always put patients interests first, if he is saying there is nothing more to be done then that may well be the case. The first step would be to gain an opinion of another doctor. It sounds as though the area is necrosed (dead tissue) which to my understanding is incredibly painful. Not being at all an expert in the area, I only know that this is a common reason for amputation. Other patients I know indeed have been wanting it, nigh on begging for it to be done. What sort of job does he do?