Vomiting yellow bile

[mistymay]

I have a 8 year old dog who has been vomiting a yellow spit looking substance every morning between two and eight. She seems great other then that but i am still concerned. She was at the vet about two weeks ago and they gave me antibiotics to give her because she was breathing heavy. Now i have given her all of the medication and i talked with the vet and she told me that it could be the medication upsetting her stomich. I just wanted to get a second opinion if anyone has any advice. She is eating, Drinking and playing like normal so i just dont know what else it could be.

Thank you!