Low blood sugar? Low blood pressure? Or what?

So sometimes my vision will fade to black, my ears will feel all tingly, sort of like when you sit on your hand for a long time, my hearing will fade and sometimes I'll hear a high pitch sound along with that, my whole head will feel light, my lips will go pale, I'll get a cold sweat and I can't stand and sometimes breathing will become difficult. This is frequently accompanied by nausea. These symptoms can last anywhere from a few min to an hour with generally just the nausea and the light, tingly, "asleep" feeling (but moved down to my feet and hands) lasting for over thirty min. I have no clue what causes this, it just happens randomly. I can be standing or sitting down when these symptoms come on although if I'm standing I must sit down or I will collapse. My friends who have witnessed it suggested it could be low blood sugar or blood pressure but those are just guesses, the obvious solution would be to go to the doctor but I would like some knowledge about what could be happening so I can be better versed when I go to the doctor, or even better yet, avoid going to the doctor at all. I'm only 17 and this obviously isn't normal. Any suggestions or anyone who's experienced the same thing or even similar?