I break out in a bright red rash every time I swim at a local outdoor pool. Never happened before this summer, but has now happened three successive times. Mildly itchy, does not appear where clothing is worn (like under bathing suit, or when trunk covered by shirt). Does appear on front and back of legs, feet , front and back of arms, and scattered across front and back of trunk if no shirt worn. Onset is about 15 minutes after I enter pool. Disappears about 30-45 minutes after I leave pool. I m generally in the pool 45 minutes doing a workout. Seems to be independent of whether I have applied sunscreen or not. Was swimming inside until about 3 weeks ago, without rash (different pool). Only new medicines I m on that I did not take last summer when I swam at same outdoor pool are Coumidin and metropolol. No new foods, detergents, clothing, bathing suits, sunscreen products. Any ideas?