RNA PCR is not recommended as a primary diagnostic test, and is only intended for early detection following a high-risk exposure with someone known to be HIV+. Headaches and a high temp alone, without other symptoms, is not indicative of HIV infection.
I second CurfewX, you don't qualify for this test, if we look at it from a standpoint of an HIV testing protocol.
PCR RNA is an expensive test, it is your money, if you wish to spend on it, you should know that you will still have to get an antibody test at 6 weeks or a IV Generation HIV test at 4 weeks for a conclusive result.
If you wish to go for it, I recommend it between 11-13 days post exposure, an undetected RNA NAT will be a very strong indicator that you don't have the virus.
You could save some money, perhaps if you can get a IV generation HIV test in the next couple of days, this tests detects antibodies and a viral protein called P24 in tandem, in most cases, this protein peaks at about 14/15 days post infection, absence of this antigen at this juncture will be a very strong indicator. The antibody part of this test will not be result oriented though.
I repeat, the above information is not substitute for a conclusive that can be only achieved at 6 week with an antibody test or 4 weeks with a IV Generation of HIV test.
If you can, you must try and reach out to your partner and simply ask about his STD status and testing history, most people don't lie when they are asked about it directly.
We wish you the best.