You need to get tested. I would like to tell you the odds are in your favor, but than I would be lying; anal sex is a high risk exposure. Go and get tested and I hope you come out negative.
Read my sentence as follows
"Not everyone get infected even if he/she has done unprotected sex with an infected partner."
Unprotected sex with known, mutually committed monogamous partner is absolutely safe because you can not give something which you do not have.
We are all humans, bound to commit mistakes. And mistakes associated with sex are more justifyable because they are linked with one of a very strong desire, nature has given to every man and woman.
To answer your question, good thing is, HIV is not a very easy virus to transmit and not everyone get infected even if he / she has done unprotected sex. However having said that, fact is, unprotected anal and vaginal sex are the only known sexual routes of transmission known to mankind as of today.
Do not focus mush on your sysmptoms because they do not mean much. If your last unprotected exposure was 3 months or old, go and get your self tested for HIV antibody, get a conclusive report of your current status.