Thanks so much for all your responses - they were super helpful!
I took her to the vet and you wouldn't believe it but turns out she has tonsillitis! I didn't even know dogs could get that but apparently it's more common in small breeds.
I also found out that she has a lot of tartar accumulation on her teeth and that's a very common cause for dogs to develop a sore throat since there's so much bacteria present in their mouth. Throwing up liquid is usually not super common but he said she could have thrown up since she would constantly gag at night like something was stuck inside her and that's a symptom for swollen/painful tonsils.
The vet prescribed her antibiotics and gave her two shots to reduce inflammation and reduce the pain. She is also scheduled for a professional teeth cleaning next week once she feels better and the antibiotics have fully kicked in.
She actually seems to be doing a lot better already. No throwing up last night and she ate her food this morning - she was very happy to eat like her usual self. I boiled her some chicken for dinner tonight like you recommended and the vet told me to add water to her dry food (to make it less harsh on her throat) and she gobbled it right up.
We have to make sure that the vomiting does not reoccur (so that there's nothing else going on like pancreatitis, etc.) and her teeth stay sparkly white and clean but I'm keeping my fingers crossed.
