doctor how a you.My question is how comes that me...

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Regarding what you mentioned, the history of sexual intercourse without using a condom , so this carries a risk of getting sexual transmitted diseases STDs such as HIV.
I do HIV test after the history of that unprotected sexual intercourse and it was negative ?
Yes this can make the possibility of the infection less likely .

The sexual partner is tested positive for HIV ?

In this situation you have to repeat the HIV tests such as combo test in order to rule out the possibility of infection.

What should I do in this case?

You have to visit your GP doctor so that the doctor could do a full clinical evaluation of your case then he will treat it accordingly.
  Stay well.   
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