Ok so my 2 week old is starting to eat 4oz

Lately she's been looking sad and I figured out its because her tummy has been hurting but I try to feed her only 3oz max but she still seems hungry after that. She's sleeping wit my mom right now and she's sleeping on her tummy (of course my mom is keeping an eye on her) but that's the only way she would fall asleep idk what to do about it