if you're swimming in a chlorinated pool, then honestly just a thorough shower with shower gel really helps. you can even get the special anti-chlorine stuff in some sports shops. you'll know you're clean when you can't smell the chlorine off your skin! and then a nice thick layer of something like Nivea Creme, it's paraffin-based & v v hydrating. but there's also the option that you're just allergic to chlorine. a clue is if you sneeze or get a runny nose after 🥸