Wow, @koolkatxx, so many replies just dismissing this horrible 'error' because 'mistakes happen'. Yes, they do, and probably far more than we realise. However, I am not saying that what I am about to suggest is the more likely correct scenario, as I don't think that it is - I do think that the majority of Mumsnetters are probably correct in this instance - as most of us have already agreed, that yes, mistakes happen, I feel (as my name above shows) that I need to express my own reaction to this thread of yours OP, so please don't get even more stressed by this rather unlikely possibility:
As most of us here have agreed, mistakes can, and do, happen; but what if it was the person who replied to your original query about the adding of Chlamydia to your test result, was the one who made the original mistake?
I certainly don't think it is impossible that there were two differing test results on the system at the same time, as that is exactly what you have described to us as having actually happened OP. So, maybe there had been an initial result/report that had just published the original result, which showed that you did indeed have thrush, but then, as an overlooked test result came in, it - the computer - then published a second report, that added that you were also suffering from Chlamydia? Maybe when you checked the results you were able to (perhaps accidentally, and obviously unknowingly) access the second report, whereas the others only saw the first one?
The only other - at all reasonable - explanation that I can think of, is that one of you must be deliberately lying, and I am not sure how you would benefit from doing so? Therefore, if I were you koolkat, I would be politely demanding a completely fresh test, so that I could put my mind to rest - sorry.