thewho - PTSD follows significant trauma. If I'm reading your post right, you've had a general fear of HIV for awhile, and now that you've heard that a friend of yours might have contracted HIV, you've been much more anxious about it. Although you note in your post that it isn't realistic that you've actually been exposed yourself.
What your experiencing might better be classified as a generalized anxiety, or even specifically hypochondria, which is an anxiety disorder based on fear of illness.
Here's more information:
http://www.medicalnewstoday.com/articles/9983.php
If you look through the HIV forum, and the STD forum you'll see a lot of people who are experiencing what you are - that despite the fact that they know these fears are unlikely, they are consumed by them.
Have you tried writing this to yourself? For me, writing things and seeing them on paper is helpful. In two columns, reasons why I think I have HIV, and then the next column, reasons why this seems unlikely.
I wish you well. Hope you post back.
How are you doing did you get any help? sometimes really good to talk ,let us know.
See your doctor. Tell him how this has affected your life, and the way you feel. follow up with a counselor.
You are probably stressing your self out with the scary thoughts, and you do sound anxious, if you have reason to think you may have contracted anything you can ease you mind by getting it checked out, if it is a matter of stress ,perhaps you can distract your self when you feel the anxious thoughts popping up, I have done that a lot and have got into the habit of giving myself a few mins to obsess about a worry then I put it away, it sounds simplistic, takes a bit of practise but it works,there are some good Natural supplements out there and some folks including me have found 5HTP low dose taken for a few weeks a help, also Sam-E has helped me ,same thing.I dont think what you say is irrational ,is it possible that something else in your life is upsetting you, Good luck let us know how you are doing .
See your doctor. Tell him how this has affected your life, and the way you feel. follow up with a counselor.