My 4yr old female yorkie has been vomiting up bright yellow foamy mucus in the mornings, not every morning. She wheezes a little immediately after. Then she eats and drinks and plays like nothing has even happened. Should I be concerned? Also, I will be making an appointment to get her teeth cleaned under general anesthesia soon. She has a history of tracheal collapse and allergic reactions to vaccinations. Any advice/info? We are new here. Thanks!