Hello. Thank you for writing to us at healthcaremagic
Flu like symptoms such as these are not diagnostic of
HIV and in your case, I don't think that these symptoms are related to HIV infection.
It is very unlikely that one will develop flu like symptoms to new HIV infection just a day after contact. HIV related flu like symptoms usually develop 1 to 6 weeks after infection is acquired.
Since you say that the condom covered almost 3/4th of your penis, it must have covered the
glans and business end of the penis. Therefore, your this particular sexual encounter can be considered as a protected one.
HIV cannot enter human body through Intact skin on the base of penile shaft. Therefore I think that you are absolutely safe as far as HIV is concerned.
However, for your own peace of mind, you may take up a screening test for HIV at 1 months after this particular sexual encounter.
Most likely the test will turn out as negative.
Regards