My female atiel laid an egg and didn't sit on it what do i do and how do i go about it plz help me?

help me plz i thought my atiel was a male but he, she just laid an egg but didn't lay anymore its been 2 days now and she and the atiel i thought was female who now i think is the male keep inspecting the nest box with the one egg and keep altering it wat do i do this is the first time my birds have ever laid eggs (egg) im scared plz help me i dnt want anything to happen to the mother. and what food do i feed them and should i put the other atiels i have (2) in a nother cage and leave the mother and father alone. and how do i no if the egss are fertile plzzzzzzzzz help.