After One To Three Hours With My CPAP Machine, My

After one to three hours with my CPAP machine, my nasal passages swell shut and I can't breathe through my nose. This continues throughout the rest of the night, even after breaks of up to an hour. I had the surgery for nasal obstructions several years ago and a recent exam showed no problems. My CPAP pressure is 15; I had this problem with BiPap and went back to CPAP. My ENT recommend Nasocort or Flonase; after three months use, these have not resulted in any relief. I take generic Sudafed (prescription) and generic Claritin (OTC). Also on BP and Cholesterol medication.