My One month Baby won't eat??

Leah

We went to the pediatrician today to be checked for thrush. She doesn't have it thankfully but that doesn't change the fact that I have been struggling to feed her for the past 2 days now. She won't keep any food down and she also didn't sleep at all last night. She isn't fussy tonight but she was pretty upset yesterday. The pediatrician we saw wasn't her normal one and she said that her weight was good so nothing was abnormal.

When she was 2 weeks, we had a really bad congestion problem. Could this be a reason why she wont eat? She still sounds a little congested and I've been doing the saline drops treatment. She doesn't have gas issues. I just worry she isn't eating enough. Is this normal? For babies around a month old?