For those of us without the option to see an allergist, might it possible to enact a kind of desensitization through a controlled schedule of O's? I'm thinking about how people go on elimination diets then slowly reintroduce problem foods with great results.
I also know it's common for POIS sufferers to experience little to no symptoms with an O following a long period of abstinence. These folks might have a strong allergic component to their POIS.
The dose of allergen is high with ejaculation, so perhaps a long period of initial abstinence is required. One could experiment with the length of time required for an asymptomatic O. Abstinence lengths could be reduced carefully, ever so slightly - while exponentially more healthy O's are reintroduced over time.
Before I knew what POIS was, and when it was really bad, I believe I may have unwittingly done this with some success. I self-diagnosed POIS as a DeltaFosB/dopamine downregulation issue for which the treatment is coincidentally similar, but not good enough. Treating it like a desens protocol would require a lot more care and meticulousness.
But I did go from having guaranteed, full blown, life ruining POIS for 4-5 days, to now a manageable POIS of a few hours-days with a crude abstinence protocol and some methods I picked up from this site.