Eurasian Kestrel, fluffy, yellow spot inside her mouth, vomiting.

[LDShaban]

My female Kestrel is not eating, it has small yellow spot inside her mouth. I took her to the vet and he gave me a pill (Anti-Bacterial) and told me to hand feed it, it was good for 3 days and yesterday I found her vomiting! it never happened to it before. I think I gave her more because she was better! and the yellow spot is reducing its size. don't you think it was the reason of her vomiting? or if there is any other reason?

Thank you all.