1) Test results are not changed by
symptoms,
and test results always overrule both
symptoms and exposure history. Even if you had a very high risk exposure, and even if your symptoms suggested HIV (which they do not), the test results prove you were not infected.
2) Dizziness, by itself, is not a symptom of HIV. This symptom is unrelated to HIV, any STD, and to your sexual exposure a few weeks earlier.