Thanks for your query to us.
there are two issues in your case 1. if you really have syncope
or you have a very close possibility of seizures. Seizures are favored if you have history of tongue bite
to head & presence of aura.
2. If you have syncope it is important to know if it is cardiac or non-cardiac. If ECG and ECHO are non-contributory, A holter monitoring at time of seizure will definitely help in excluding cardiac cause. Two other important causes of syncope are neurocardiogenic syncope & pure neurological syncope.
Hope this helps