What Causes Sudden Blacking Out, Ringing In The Ears, Dilated Pupils, And Loss Of Consciousness Like I Experienced Last Night?

last night was one of the scariest moments of my life, i was washing my face and my vison started going black from the bottom up and my ears started ringing super loud, then i blacked out, but my friend who was with me told me my pupils got super dilated then i fell forward and slammed my head in the mirror then fell back onto the ground and i had my eyes open the whole time but it felt like i was dreaming, what was it?