rash from swimming

Hi there,

I was hoping I could get some good advice. I have developed a rash on my upper shoulders, upper back, both sides of my nose and chin and my upper chest right after swimming in the pool. ( this does not happen in open water swimming). The rash breaks out 6 hours after swimming regardless if I have taken a shower after the swim or not. I look like I have chicken pox and it feels like tiny hot needles are piercing my skin. I tried Benadryl ointment but to no avail. I am hoping that I have not developed an allergy to chlorine. Is that even possible? Any ideas would be appreciated.