Signed up specifically to respond to this post.
I believe you are correct. I started having very severe reactions to orgasms back in 2006 and the reactions correlated with more intense porn use. However, correlations do not necessarily equate to causation.
It turns out that I have pretty severe general autoimmune issues, including some form of eosinophilia and/or Crohn's in the gastrointestinal system, autoimmune thyroiditis which flares up sometimes, and other issues.
For many years I assumed I was just addicted to porn and porn was causing the problem. Turns out, it's a disease so at least I don't have to feel guilty anymore.
My POIS symptoms include:
1. Extreme fatigue to the point where I can't get out of bed
2. Very severe back muscle pain to the point where I feel like I'm going to pass out of I stand up.
3. Severe gastrointestinal disturbances (ulcers, acid reflux, passing blood and undigested food in the stool, very severe pain in the stomach and colon)
4. Severe psychological problems (social anxiety, inability to make eye contact)
5. Loss of ability to properly pronounce certain syllables/letters when I speak (I sound like I'm slurring my words).
6.Memory loss that becomes severe if I eat the wrong foods.
These same symptoms are brought on by eating foods to which I am intolerant and eating these foods markedly worsens the POIS.
I eat an extremely bland diet now which helps:
1. Ground beef with only salt added
2. Soda
3. Chocolate skim milk (made from powder without vitamin fortification)
4. Plain potato chips fried in coconut oil
Additionally, I have found three substances that greatly help my POIS:
1. Sugar. Sugar eliminates much of the psychological and system symptoms. Large amounts of it. I'm talking in the hundreds of grams per day range. Check out Ray Peat's ideas on sugar. I believe sugar is superior to complex carbohydrates for a number of reasons. I'm specifically talking about white table sugar, soda, or fruit juice. I am not talking about cakes, candies, pastries, or ice cream because these contain many other toxic ingredients (polyunsaturated fat being the worst of them).
2. Caffeine. Caffeine seems to help with the neurochemistry and definitely elminates most of the fatigue.
3. Chocolate. Probably has similar benefits to caffeine since it contains small amounts of caffeine and theobromine.