Shalom, my father is a guer. He without knowing was working on Shabbes, because he thought that there was pikuaj nefesh for goyim. He is a doctor. Now he knows there is not, the question is, is the money that he recieved for his wor kasher or not
In fact a Jewish doctor who deals in areas of Pikuach Nefesh, ans is faced with a situation of pikuach nefesh for a non Jew, would be permitted to engage in saving him, even if this would include chilul Shabbos. This is due to a concern of “Aivah”, causing animosity between Jews and non Jews which may lead to life threatening situations and his hence permitted.