Hello I want to make a thing very clear that you are NOT having HIV infection : P 24 ENZYME IMMUNOASSAY ( ELISA ) test is specific and most sensitive and this NEGATIVE in your case. Finger prick test is also specific and reliable in your case and this is NEGATIVE for HIV infection. 3rd point is that you are having only oral thrush , nothing other symptoms resembling HIV infection , so NO chance of getting HIV infection by you. Now about main question , why are you having oral thrush after 10 days of sexual intercourse with sex worker ( UNPROTECTED ). This type of thrush may be due to CANDIDA infection. Candida is a ubiquitous in nature and inhabits the G I tract , THE FEMALE GENITAL tract ( and you got this infection due to unprotected sex ) and the skin. In your case this is mucocutaneous candidiasis :thrush is characterized by white , adherent , painless, discreet or confluent patches in mouth, tongue or esophagus. Diagnosis can be confirmed by established by visualization of pseudohyphae or hyphae in the presence of inflammation in appropriate clinical sample. Usually azoles ( fluconazole or itraconazole ) are most appropriate medicine . Alternatively nystatin . In my opinion don t worry , consult a DERMATOLOGIST and take his treatment . Hope this will help you.