Hey! I'm so glad I saw this thread because I've actually been diagnosed with Hypochondriasis Anxiety (health anxiety) so I know exactly what you're going through.
Hypochondria is actually a medical term (although people use it jokingly) and it's basically an irrational fear of illness. It takes different forms in different people. For example, I was convinced I was dying of cancer and constantly checked my body for lumps, and ate tons to make sure I didn't lose weight (I knew that sudden weight loss was a sign of cancer). I could tell you the symptoms for any number of diseases and was afraid of them all. Like you and your sleep problems, I had a health scare which triggered all these feelings, but unlike you, I wasn't scared to go to the doctors. Well, I was scared of what they'd tell me when I got there, but going and getting an answer was easier than sitting and driving myself mad with anxiety. But avoiding doctors altogether is also normal.
Your exhaustion and dizzy spells are more than likely something to do with anxiety. I don't want to come across as diagnosing you though, so maybe have a read of this link :
http://www.bbc.co.uk/dna/h2g2/A3022101 and if you can relate, maybe start thinking about talking to someone about it. Ignore the bit about having to have symptoms for 6 months before doing anything about it, because I had symptoms for less than 2 months. I know it will be hard for you to go to a doctor but if you do have some sort of health anxiety problem, doctors are the best people to help make you feel better.
Good luck.
