Hi Seahorse,
I'm sorry you're feeling so bad at the moment. You know, things can get better, at any moment in life things are just as likely to take a turn for the better as for the worse. Don't be scared.
I think you should definitely get your symptoms checked out, firstly to make sure it isn't anything serious, and secondly because otherwise you'll always have doubts in your mind and think there is something wrong with you, they're just not looking properly. And if you feel your doctor isn't taking you seriously because you're already in their 'hypochondriac' drawer then go to another one. And if that one isn't any good then go to the next one, until you find one you trust and are comfortable with. They get paid to help you, and you have a right to be taken seriously!
I'm not a doctor but I think that there may well be some physical problem, but there is absolutely no reason to think that it is something dangerous. It is much more likely to be a cramp or trapped nerve or something to do with your sleeping position. Your body is a living changing thing, and pains and numbnesses do occur, it's quite normal. Bodies are really good at fixing themselves, and it doesn't happen very often that young people just die out of the blue. Someone else who is less anxious may well experience the same symptoms as you but doesn't give it a second thought. But through the panic and anxiety it just gets blown completely out of proportion.
Try to separate the physical symptoms that scare you (numbness, pins and needles) from the symptoms the adrenaline is causing (dizzyness, nausea, unreality). Read the first bit of the panic program on this site, it's all explained in there.
Here are some facts that are worth keeping in mind:
1. Hypochondriacs always see the most fatal but least likely outcome.
2. What feels like missing heart beats is called extrasystols. Although they feel very scary they are utterly normal and my doc assures me that in all his career he has never ever seen them turn into anything nasty.
3. Just because something feels dangerous doesn't mean that it is. Your symptoms are real and they may be painful and/or scary, but this bears no correlation to how dangerous they are.
Sorry this has got so long. I wish you all the best with al