What Causes Persistent Sneezing At Night?

I am having problem with my C-PAP machine. It has happened a few times and now it is every week or more. I wake up in the middle of the night and start sneezing and it lasts for the whole next day. Just one sneezing sequence after another. I am miserable. I thought I might need to clean the machine more often also. Now I just don't know.
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