With that in mind, this constant balance needs to uphold in order for us to adjust with our daily activities. In some people who may be more prone or susceptible to either of the two systems, small triggers can lead to a moment of overly reactive tone without allowing the other system to counter-balance. Which in the case of fainting, the hyper-vagal state had a long enough time to overwhelm the body and thus succumb to changes in the body leading to fainting. Without stating that this is definitely what is going on with your recurrent and now increasingly frequent fainting spells, severe pain, emotional stress, or even something as normal as having a bowel movement, are some examples of such triggers. These types of fainting episodes usually have some sort of noticeable symptom complex preceding the event, called a prodrome.
In response to your second question as to what you should do, every person who has frequent faint spells should be evaluated properly. Although vasovagal syncope is known to be the most frequent cause of loss of consciousness, it is more of a diagnosis of exclusion after more serious causes have been looked into and ruled out. Some of these other, more serious causes of fainting include neurologic disorders such as seizures, or cardiovascular disorders that include arrhythmias (irregular rhythm of the heart).
Therefore, you should see your doctor and have your history and symptoms carefully evaluated, then have them refer you to a specialist such as a cardiologist or neurologist for further evaluation and possible treatment.