Hello dear Sudden onset loss of consciousness at such young age may be due to seizure, cardiac arrhythmia or sometime conversion reaction. If loss of consciousness is associated with tonic posture, frothing, tongue bite or incontinence then seizure is the possibility. History of palpitations, chest pain, sweating, pallor associated with loss of consciousness may be due to cardiac cause. Loss of consciousness related to standing posture may be due to syncopal attack. And lastly if everything comes out normal then a possibility of conversion reaction has to be kept. Brain imaging, eeg, ecg and 2d echo needs to be done. Hope he recovers early God bless him Dr Neeraj Kumar Neurologist