my girl is 3 weeks old. she's having flu and cough. went to pd and pd said it's normal for babies to have phlegm. and coz she's too small, there is no medication. but my qns is her appetite has went down and she always wanna sleep. every feeding only 20 to 40ml. and she will sleep for 5 to 6 hrs. shld I wake her up to feed her? or is sleeping a way of recuperating?