I had the same Rash going on after soaking in the deepest pool next to the crab cooker, took about 2 weeks for it to go away fully and I used blue emu cream to get rid of it only thing that helped me.
heard that it is either swimmers itch or Pseudomonas aeruginosa folliculitis (aka hot tub folliculitis) and to rise off with vinegar or lemon juice right after you get out of the water and to towel dry never air, as to use coconut oil or a sun screen befor you get into the water to help the water not soak in to the pores as much. Thank god I'm not the only one who experienced this.