Hello Oral and anal sex , unprotected sex . Red bump around groin area , just after 3 days of exposure , it is very difficult to say , that this bump is due to HIV or not . Antibodies to HIV begin to appear within 2 weeks of primary infection . Approximately 50-70 % of infected individuals experience an acute syndrome following primary infection . The acute syndrome follows infection by 3-6 weeks ( in your case this bump is just after 3 days , so questionable ?). There is a strong association of transmission of HIV with receptive anal intercourse, probably because only a thin , fragile rectal mucosal membrane separates the deposited semen from potentially susceptible cells in and beneath the mucosa and trauma may be associated with anal intercourse.Anal douching and sexual practices that traumatized the rectal mucosa also increase the likelihood of HIV infection . So , you are at higher risk case ,so get in rapid nucleic acid amplification test ( P 24 pcr , rna ) . The groin bump may be due to bacterial infection so take azithromycin +levofloxacin combination for 5 days . As I mentioned above get in this test after 2-3 weeks of initial primary infection.