Thank you for this interesting question, and I am sorry to hear about this persistent issue you have been experiencing. In order to provide an accurate diagnosis, a physician would need to collect a complete medical history, including the details of prior testing. The doctor
would also need to perform a thorough physical exam. You may require additional testing, as well. Therefore, I strongly encourage you to schedule an appointment with a cardiologist
to further discuss this issue.
Syncope is defined as a sudden loss of consciousness and postural tone with spontaneous resolution. Your description sounds somewhat atypical for syncope, but I would need more information to know for sure. Heart arrhythmias that cause your heart to either beat rapidly or extremely slowly can cause syncope, and patients often need to undergo longterm EKG
monitoring to rule this out. A transthoracic echocardiogram is also useful to evaluate for structural heart disease. You may need to undergo a tilt table test to rule out dysautonomia as a cause. As you mention, seizure is a potential cause, and longterm EEG monitoring is often required to evaluate this. POTS disorder is essentially a diagnosis of exclusion, and it is important to rule out more serious causes of syncope first. Therefore, I encourage you to see a cardiologist.