Hi OP, I work in HIV and sexual health, so I wanted to come on and reassure you. What I suspect you are experiencing is being a bit run down - maybe because it's that time of year when all of our immune systems are run down, maybe because you are feeling anxious and stressed. It is very unlikely that you would acquire HIV even from an exposure to someone who is HIV+. These days nearly everyone is on treatment which makes it impossible for them to transmit HIV to their sexual partners. It's, of course, very unlikely that your partner had HIV anyway, as the prevalence is very low in the general population of heterosexual men (I'm making the assumption here that he would fit in that group, of course).
All that being said, it takes usually a decade on average or longer for most people to start to experience significant symptoms of HIV infection like weigh loss. Those images we see from the 80s of skeletal men very ill, those were not people who acquired HIV at that point in their lives, but people who had gotten HIV in the 70s. You would not experience that sort of symptom from getting HIV earlier in the year - even in the unlikely event that actually happened.
I would imagine you are just stressed, run down, maybe dealing with other health issues - or maybe just struggling with anxiety, which is causing your immune system to go haywire.
All that being said, HIV is a very manageable long term condition now. I have lots of people in my personal and professional lives who are living with HIV and have been, some of them, since the 80s or 90s. In fact, I was speaking with a friend yesterday who is a woman living HIV (she acquired HIV at birth from her mother, so has been living with HIV for 30 years now) and I was reflecting as we were talking that she probably does less to manage her HIV than I do to manage my health condition (I have a damaged pancreas). She take 1 tablet a day and sees her doctor twice a year for 20 minutes. I take 6+ tablets a day, plus vitamin supplements, and also see my doctor maybe 1-2 times a year. She probably has a more 'normal' life than I do (stigma aside) in terms of just dealing with health stuff day to day.