You should see a doctor about this as it is a new symptom. It could be due to esophageal spasms which is when you swallow and your esophagus just does the wrong thing. When this happens food can get stuck and you may need to vomit.

You can read more about esophageal spasms here:

http://www.healthcentral.com/encyclopedia/408/374.html

This can be caused by reflux or may be a symptom by itself. But, any time you start having troubles with swallowing you need to get it checked to make sure it's not something more severe. While unlikely, esophageal cancer can also cause problems with swallowing.

You may also want to try to track when it happens. Is it more common with hot or cold foods? Firmer textures or softer foods? All of this will be useful for diagnosing you.

Stephanie