i had unprotected vaginal sex on the 21/11/2018, I then noticed severe oral thrush a couple of weeks later, i  went and tested for HIV with the following; Cepheid Rapid RNA HIV-1 Qualitative at 18 days post exposure, Negative 

Welcome to the Forum.  I'll be glad to comment.  The answer is that you have certainly ruled out the possibility of having acquired HIV.  While many manufacturers claim  the RNA tests such as the Cepheid test is completely reliable after 11-14 days, most experts would validate this later with a combination HIV antigen/antibody test such as you took at day 28.  When used alone combination HIV antigen/antibody tests are more than 99% sensitive at 4 weeks after an exposure and 100% conclusive at 6 weeks.  In your case the combination of the two tests at the time you took them make your results conclusive. No further testing is needed.  

I realize the having thrush may have increased your concern about HIV however in the face of negative tests, you can be sure that your thrush was not HIV-related.  I should add that most people who get thrust do not have HIV.  Factors which particularly increase the likelihood of thrush include taking antibiotics or having diabetes and that most people who get thrush have no risk factors at all.

Bottom line, you are in the clear and can be confident that you did not acquire HIV following unprotected vaginal sex on Nov. 21.  

I hope this comment is helpful.  EWH

Thank you for your reply it has definitely helped me. I know this follow up is from a while  ago but any reply would help. 

I tested for

On day 18 along with the RNA

I then tested for 

syphallis (IgG/IgM by EIA), 

On day 28 with the DUO, 

My question would be are these tests also conclusive? I have had the oral thrush for around 4-5 weeks now and does not seem to get much better with Daktarin. I also noticed a rash on my body a few days after my last post, very small round reddish dots, I say reddish as the actual colour is pale red, on my arms, thighs, chest, top half of my stomach, and face, it comes and goes, can move in those specific areas, is more visible after a hot shower or if I have been laid on that area causing pressure, say if I have laid on my chest and stomach while asleep. Reason I ask is I have never noticed a rash on my face after a hot shower before. Would you recommend testing for anything else again, I understand symptoms are not a result, but an expert opinion would help. 

Thanks

Yes, these test results are conclusive.  I see no need for additional testing.

I cannot offer a clear diagnosis for either your rash or your oral symptoms.  If you have recently taken antibiotics, these could contribute to the likelihood of either one.  I suggest you seek evaluation from a health care provider related to these problems. They are unlikely to be due to an STI.  EWH