New born baby feeding less

Sandy

Hello Mommies

My new born of 3 weeks was eating extremely well and gained a considerable amount of weight the second week ( from 2.6 to 3KGs in one week) but now she is not eating the same she is eating a lot less and sleeping more. i cannot wake her up for feedings and when she does it is very small amount compared to before.

Does anyone has any experience and could tell me what the problem could be??