If anyone knows the answer to this please, any opinions are very helpful!

So I have been gone for a month and two weeks and I left my little baby at home with relatives. I got home today and I noticed that she is very small! I asked if she had been eating, and I was told once a day but had been drinking water more. Was she not eating because I was gone for so long? Or.. is this normal for a Maltese mix? This was the longest I’ve been apart from her. I’m kinda worried :(

(Old pic is provided !)