The sudden urge to vomit with no other obvious cause is something that should always be evaluated by a physician. There are many reasons that this could be happening. If you have recently started a medication, you may be getting the urge to vomit from this. Your mouth watering suggests that maybe you may be experiencing reflux from your stomach into your esophagus. This can cause your mouth to water like you are going to vomit and often the urge to vomit. Although they are quite rare, certain brain tumors can cause sudden urge to vomit. These episodes are not usually preceded by mouth watering. Finally, you may have a very mild gastrointestinal viral infection that is only causing this one symptom. If this is the case, your symptoms should improve quickly.
I suggest that you schedule an appointment with your primary care physician
. He or she can take a more detailed history of your symptoms and perform a comprehensive physical exam including a neurological exam. It may be that your doctor
will see this as an issue with your stomach such as reflux. If this is the case you can get a medication to help with this. If not, you may require more testing. Good luck.