I would keep a journal and write down exactly when there is an episode of vomiting and how often. If she is gaining weight and eating a variety of foods, you can wait a few weeks or even a few months before returning to the doctor. I find that making a specific appointment to discuss a health issue is helpful. If you discuss a problem during a well check up and everything else (weight, blood tests, etc) are normal, it is easy for the doctor to be reassured and not explore the problem any further. Also, doctors know that some symptoms just come and go for no reason.
When you make a separate "sick visit" the doctor can really concentrate on the problem presented.
It is not common or normal for a two year old to vomit or complain of throat pain. Your doctor needs to rule out: Gastroesophageal Reflux (GER), Gastroesophageal Reflux Disease (GERD), food allergies, food intolerance such as lactose intolerance or fructose intolerance.
Before you go to the doctor, be sure to keep track of all food and drinks (amount and type of food, when eaten) for about 3 days. This will give the doctor a picture of a typical diet and intake.
By the way, did your daughter have colic or reflux as a baby? Sometimes parents tell me their baby "outgrew" reflux or colic and it mysteriously returns later. Just curious.
Keep advocating for your daughter. You are her voice!
The Reflux Mom