I'm sorry Eeva is not acting like herself. As you suspect, it might possibly be due to depression or separation anxiety that her owner is away.
If she's not interested in eating, this can cause a serious liver problem, if it continues. The smell from her butt may be because she's not grooming properly, as you suspect, but it can also indicate a problem with her anal glands; if they are impacted or infected, they may be leaking and this can lead to a rupture, which is painful and prone to infection.
She may not feel well in general and have one or more underlying medical problem, in addition to missing her human mom, so it would be best to have her seen by a vet or ER vet, as soon as possible, to be diagnosed and treated.
I hope all will be well with Eeva!
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