I have new information that could be valuable.
I realized that when I have an orgasm with a very hard penis, I have no symptoms.
Many who suffer from POIS have anxiety and have difficulty maintaining a strong erection and often experience premature ejaculation.
In my case as I never had symptoms when orgasm happens with traditional sexual intercourse (with a partner) I always suspected that there could be some relationship with adequate blood flow to the genital region.
I decided to experiment with masturbation. I was very relaxed in a very calm and private environment and maintained a good erection for a few minutes before ejaculating and had no symptoms after orgasm, not even the traditional fatigue that practically everyone has after an orgasm (even those who don't suffer from POIS) . As I use Sertraline 50 mg (1 x a day), ejaculation does not come as fast as if I were without the medication. So I suggest you try starting therapy to reduce anxiety, preferably with medication that increases the availability of serotonin.
It's not a definite certainty because I had these orgasms 1 week apart. Maybe if you increase the frequency the result can be different.