allergy only to pools in one state????

I used to swim daily in my university pool as a graduate student. I also used some other aquatic centers in the area. I moved to another state for a job (Minnesota), and I'm experiencing the horrible allergic-type reactions (throat swelling, hives, sneezing, congestion that lasts for days, breathing issues) that some have posted about here. None of the explanations, however, seem to apply to me, because: 1. I ONLY seem to have this reaction in Minnesota pools. When I went back to two other states recently, I used community and university pools, crowded/not crowded, cloudy/not cloudy, with ZERO reaction. I have never seemed to react to ANY other pool. If this were an acquired sensitivity, why would it all of a sudden shut off in another state? I swam in both the local YMCA pool (nasty and cloudy), and at my university pool in MN (clean and empty, also used by swim team), same reaction, same severity for both. 2. I tried a saline pool at a fancy gym about an hour away once last fall. I would not be able to afford to go there just to swim, but I wanted a data point. I did better, but was still sneezy and generally not well for a day or two after. Again, in at least two other states, without regard to the maintenance of the pool, I have had NO reaction whatsoever. I have seasonal allergies, but have had them all along. I take antihistamines daily. I have had no increase in other allergy issues since moving here. I would really like to be able to swim again, and I can't easily move to another state. There is one other lap pool in my area I can try, but I'm afraid of getting sick again. Has THIS particular type of issue arisen for anyone else?