Hello, I have a problem, every time I take a swim in a lake or a river, my nose gets blocked. This doesn t happen immediately, but later when I m already sleeping ( Usually I just wake up in the middle of the night, duo to difficulties to breathe). But This doesn t happen when I m swimming in pool or in salty water (sea, ocean). What could be the problem? And what is the solution for it ? Thanks, I am 25 years old, 1,80 m tall, 76 kg weight, healthy guy.