We're hoping to compare notes with people w cf who run. My 15-year-old son runs cross-country and finds that if he tries to breathe through his nose when he's running, he immediately gets a wave of nausea. There is no problem as long as he breathes through his mouth. Also, when he gets up suddenly from lying down, he feels as though he's going to pass out. He has the typical sinus problems that go with cf, and we're wondering if this could lead to inner-ear sensitivity. Has anyone else had problems like this, or is it just something particular to Jordan?