Bethany
If she is not eating then that's probably why she's lethargic and throwing up.Her sugar and protein can nose dive quickly since she's a little dog.The heart failure shouldnt keep your dog from eating.I had a dog with congestive failure and he ate fine.Maybe it's the swelling or the collapsed tranchae.She needs to eat for sure even if you have to force feed her.I'd feed her small amounts so it won't make her feel sick.You could try nutrical.It's liquid food.