Any change to where you are living, even just changing apartments in same building, or renovations/construction/new carpets, even other parts of building, etc?
This is a list from trying to determine source for children/grands/friends/relatives.
Have you ever been tested for allergies?
Do you have hot air heating which can recirculate air from other apartments?
We are both going through that sneeze routine.
Changes: Full Winter has finally hit with single digits, due for negatives tonight; working outside in that weather; snow coverage; wood stove 24 hour operation (we get some smoke when open door to load more wood); cleaning or other activities that stir up dust (that can include taking a dusty book off a shelf); far as I know, weather precludes pollen. Spending time in a workshop. Cleaning for change of season. Probably etc.
In winter, house sealed, so get less flow of fresh air.
When child & grand were growing, both had allergies needing special diets, and no carpets (we ripped them out. Boy! Did that set my nose off!) Maybe you can get the carpet steam cleaned? Pet changes, even just indoors more? House sealed for winter? Rodents sneaking into house (Attic, crawl space, basement (damn squirrels, too)
We just hate those multiple explosive sneezing fits.