Lol. Most humans assume everything that doesn't have a common, socially-accepted explanation is psychosomatic.
If you have any chronic condition that affects your ability to function(surprise, most of them do), 80% of people out there will just cheerfully gaslight and abuse you without batting an eye.
It's "immune mediated", meaning that there is indeed a response by the immune system. Unsurprisingly, histamines and other inflammatory markers are detected. Sometimes anti-inflammatories can help.
I very rarely get itchy after taking a shower. It seems to be related to the level of humidity in the air wherever I am, and also time of day. It's very weird, and I can't imagine how annoying it would be to have that happen every single time you encounter water.
If you have any chronic condition that affects your ability to function(surprise, most of them do), 80% of people out there will just cheerfully gaslight and abuse you without batting an eye.