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You say little about the date of your exposure or what sort of partner you had sex with so I cannot comment on how these things might influence your risk for HIV.
I can however tell you that trying to judge whether or not you have HIV from symptoms such as those you describe is a waste of time and energy. In your case the symptoms you describe are not suggestive of the complete ARS syndrome and occurred earlier than would be typical for the ARS which typically occurs at 2-3 weeks following exposure (4 days is too soon). furthermore, it would be unusual for the rash of HIV to come and go in the way that you describe.
My guess is that your risk of HIV is low. following an encounter of the sort you describe however, it is always a good idea to get tested for common STDs such as gonorrhea and chlamydia. An HIV test performed at 4 weeks following exposure would be expected to detect over 90% of infections and at 8 weeks virtually all infections can be detected.
I hope these comments are helpful to you. EWH