The true culprit may very well be...POIS. Post-Orgasmic Illness Syndrome.
Seriously?
(Googles)
Wow. That
sucks.
The therapy would be an extremely cheap and simple one, though: just picture your parents making you... Should be sufficient to get really everything go limp
No, seriousely. You can test pretty easily if this syndrome really applies to you. If it does it should appear after every single orgasm you experience. (However, you expecting it to happen might *make* it happen).
If it's a hormonal thing (which it appears to at least be partially), it can comperatively easily be treated by supplying you with the missing hormone or the enzyme that processes it. And until then you'd simply have to avoid having an orgasm. That might be frustrating but would still be a good deal more comfortable than the alternative.
If the theory is correct that it's an allergy to one's own semen, it could easily be treated by sterilisation or by hormonally suppressing the semen production (the latter is imho not recommendable, however, as it'd have serious side effects). Personally, I consider the allergy theory rather unlikely, though not completely impossible.
I recommend you keep a precise diary of what you eat, drink, wear, do (including sex/masturbation) - any substance, object or person you come into contact with.
This way you can see if there is a connection to one or several factors.
Your problems might just as well be triggered by contact to a chemical substance, hence it'd be good to really note down everything that touches you (literally). Weather, too, in case it's air-pressure or temperature triggered. And your respective mood to find out if there's a hormonal connection.
The date is important too. It's widely unknown but men have a monthly hormonal cycle as well. And that might well trigger problems at regular intervals.
Without sufficient data there will propably be a number of possible illnesses that might apply. So the first thing your medicine men need is rock-solid (pun definitely not intended!) facts