Redness, rashes, and skin spots after showering?

I’ve been dealing with a similar condition for about 20 years now. Based on the symptoms, I’m pretty sure it’s aquagenic urticaria. Whenever I head to the coast for vacation, I try taking Zyrtec (loratadine) because of all the swimming, and it actually helps.
For me, it doesn't matter if the water is freezing or lukewarm, or if it's the ocean, a pool, tap water, or even just sweat. Any kind of moisture triggers these red wheals with a tiny white dot in the middle, plus that intense itching and skin tightness.
It usually flares up about 15 minutes after I shower or swim, and then dies down after 30 to 60 minutes. Sometimes during the summer... like when I'm at the beach... it can last up to 2 hours.

It shows up on my chest, stomach, back, neck, shoulders, and arms down to the elbows, but my legs stay clear.

I feel a bit more "resistant" in the winter, whereas in the summer, I’m way more sensitive.

I’m also allergic to penicillin, and I read somewhere that there might be a link between the two. Apparently, some people who were given massive doses of penicillin as kids to fight off infections end up with higher histamine levels, which supposedly leads to aquagenic urticaria.