Some Nigerian doctors in Saudi Arabia, the United Kingdom and the United States of America have knocked the Federal Government for its alleged failure to invest in the health care sector.   The doctors, who spoke in separate interviews with Sunday PUNCH, said the inconsistency of the government to adequately cater for the needs of medical practitioners had led to massive brain drain in the health sector.   Some of the doctors who shared their experiences with our correspondents added that they cried and felt overwhelmed when they received their first wages, which some of them described as being 10