Unusual sleeping and feeding pattern.

Hi , My baby is 2 months old. Suddenly since last 2 weeks her sleeping and eating pattern got very much erratic. She is sleeping too much in day time and entire night she is not sleeping sometimes we started trying to make her sleep from 10 PM and she is sleeping next day at 11 AM. Also her metabolism is reduced in day time as she is sleeping most of the time and and night she is becoming too hungry. As per our doctor we are giving her formula milk as top up on top of mother's milk. At night within 20-30 of every feed she is showing hunger symptoms like moving head and constantly eating her fingers and fist. Sometimes 5 minutes after feeding formula ( minimum 50 ml) or breast milk she starts eating her fist and start crying. Is it always signifies she is that hungry at night? Do we need to feed her every time she is giving symptoms like above? How can we change the erratic sleeping and eating pattern? Also she spitting up curd 4-5 times a day . Can you please guide us?