My sister is pregnant and going crazy!

Is it even possible for you too start going through mood swings and cravings wile your only 5weeks pregnant? My sister fount out she was pregnant last Saturday morning and since then everyone in the house has been her slave! She eats everyone's food saying she's craving it and she refuses to do certain things because she pregnant . Like I think she's over exaggerating the situation. And she's doing what she knows what will happen, but in the long run its gonna back fire bc she's gonna hate the pain when it really hits her. And everyone thinks she's just crying wolf.