I Have A 1 Month 3 Weeks Old Baby And

I have a 1 month 3 weeks old baby and she is unable to poop on her own. She also have a hard time to fart.she'd scream and cry terribly all day all night and very tired. Everytime i put her down to bed asleep she will be awake right away...is it safe to always stimulate her anus everytime she feels like to pass stool? Also is it safe to switch her formula milk from one to another?