Biological False Positive For Hiv

Hi
My problem is that during a screening for STDs, the clinic called and said they had a false biological positive on some aspect of the blood test fir HIV, they said to come in for a repeat blood test which I did a month or so after the original blood test. They told me that the results were exactly the same as the first time, and that this meant I was not HIV positive. I was told that there are certain things in different peoples’ blood and I have something in mine that made me test very weakly positive, but that I was not, in fact, positive, because if I was, there would have been significant changes in my blood over the elapsed time between first and second blood test.

I am still worried. Could I have HIV? I know I have been told that I don’t but it did not seem black and white, it was a very unsatisfactory explanation, and only through a phone call so I could not discuss this further.

Could the “false positive” be due to the fact that I had HPV during my first blood test? Or due to the fact that I had glandular fever nearly 4 years ago? Could prescribed drugs affect this test? What exactly is in my blood and is there any way it could turn into a dangerous virus and what can I do to prevent this?

Many thanks for any help that you can give.