Please help!! My 12 year old dog is refusing to eat.

She's a tiny chihuahua. She probably hasn't weighed more than 5 pounds in her entire life.

And she's been visibly losing weight.

She has been refusing to eat anything since my father left a few days ago (he's multiple states away, and won't be back until after the 4th of July).

I've tried to give her different types of food that I know she loves, I've tried to give her broth (which she also loves).

I've tried to eat something infront of her and see if she'd beg for it (she looked at the food, and even starred at it for a moment when I passed some of it it to her).

I've even tried to set her bed down on the kitchen floor, cutting some vegetables, and throwing some down for her, because she ALWAYS would beg for that. And she still wouldn't eat anything.

I've checked her teeth, and they look fine.

I don't know if it'd makes any sense, but she just looks sad.

She doesn't leave her bed, and even when she's outside going potty, she just lays on the grass.

I'm going to take her to the vet as soon as possible, but i am so scared that she won't even survive the night.