I get this symptom the most when fasting. Apparently when fasting, parasites
aren't getting their food and it pisses them off.
The other thing that does it to me is that it seems to be an alergic reaction to certain things. Cat fur (I have cats, they don't make me sneeze but I can't have them near my face..if I do, I need to wash it right away)
Certain colognes/perfumes also do it. I don't wear it but if I'm standing in line at a grocery store and some french whore is behind me leaving a trail.. my nose will itch.
Some guys wear cologne that doesn't bother me but others, can't stand it and it's not because of the smell.
So, in your case.. I'd say take a look around your beddroom and see if you're using anything different or anything has changed. New soap you washed your blankets/sheets in? New guy/girl in your bed? New pet? New..something? If not..try a parasite