I took my kids to a water park. A day or two later I've noticed itchy patchy red rash areas where my bathing suit was covering.?

Folliculitis. it could be a case of folliculitis, an inflammation of hair follicles. water parks despite the chlorine are sources for this. try washing area with anti-bacterial soap and applying cortisone cream 3x/day. If not imoroving in 2-3 days, see your doctor.