Go and do a search for Acute Retroviral Syndrome. I don't know all the facts, but I think most people experience it soon after their initial exposure to HIV. For me, I had flu-like symptoms about two or three weeks after being exposed. I had a fever, muscle aches, etc....
For me it just didn't feel like the normal flu though...but I think this was pyschological...I knew I had put myself at risk recently so I think I was smart enough to realize that something was up even though at the time I had no idea what ARS was. ARS rangs from mild to pretty severe in some cases...mine was fairly mild. I went to the doctor and got a viral load test and thats when I found out. If you're worried, go to the doctor, the sooner you're diagnosed the better. Hope this helps