Praise be to Allah.
From your question we sense that you are keen to find out the correct shar’i ruling and that you want to learn the teachings of your religion and what has to do with your work. We ask Allaah to help us and you to do that which pleases Allaah and to help us avoid disobeying Him or going against His commands in any of our affairs.
It is known that women are the twin halves of men in society, and that they have a great role to play in raising the next generation and in reviving the ummah. A woman may work outside her house in an appropriate job, without exposing herself to anything that goes against sharee’ah.
With regard to treating male patients, and all that it involves of mixing with them and being alone with them, this is not permissible according to sharee’ah, rather it is a fitnah (source of temptation) that the Messenger of Allaah (peace and blessings of Allaah be upon him) has warned us against. It was reported that he (peace and blessings of Allaah be upon him) said: “No man should alone with a (non-mahram) woman unless her mahram is present.” Narrated by Muslim, 3259. And he said: “I am not leaving behind me any temptation more harmful to men than women.” Narrated by al-Bukhaari, 4808; Muslim, 6881.
It is not permissible for a woman to treat a man except in cases of necessity, such as if there is no male doctor available to treat him, or if the matter cannot be delayed as in the case of accidents etc.
Shaykh Ibn Baaz (may Allaah have mercy on him) said:
“Female doctors must treat only women and male doctors must treat only men, except in cases of extreme necessity, if men are suffering a disease for which there is no male doctor available, in which case it is o.k. Allaah says (interpretation of the meaning):
‘He has explained to you in detail what is forbidden to you, except under compulsion of necessity’
Fataawa ‘Aajilah li Mansoobi’l-Sihhah, p. 29
Hence you should limit your work to treating women and children as you mentioned, and seek reward for this work with Allaah. Whoever gives up a thing for the sake of Allaah, Allaah will compensate him with something better than that.