Sometimes the body simply gets very sensitive to particles in the air. It's not exactly an allergic reaction, it's more like a tickle and irritation by something you breathe in. It's going to be very hard to eliminate everything in your house/bedroom that will set you off. Start with your bedroom and eliminate the things that may be harboring dust particles like drapes, fancy pillows, and duvets. Wipe down everything as best you can. Give it a couple of clean days and see if you sleep better. Use a damp mop on the floors if you don't have carpets. If it seems to help, and you have carpets, think about getting rid of them.

For this first extra clean dust eliminating cleaning, if you can get someone to help you, it would be very good. It might even be worthwhile to get an air filtering system for your bedroom. If you can clean up where you sleep, then it will help ease things for you for the rest of the day.

don't use perfumes, bath powders or soaps that have a fragrance. Be careful about what kind of detergent you use in the washer. No softening sheets either. No air fresheners.

I'm sure that you have already thought about most of these things, but sometimes it's easy to forget a few things. Everything that you can eliminate, makes it easier to tolerate other things. You may never be able to completely eliminate everything, but you can make things much more bearable.

Don't forget to change that filter on your air conditioner or furnace either. Keep your window and doors closed as much as possible. Fresh air is nice, but often it has air borne particles that will irritate.

I hope this helps some.
From my own personal experience, I am a terrible housekeeper.....and I pay for it by having to cough more than I should. We took up the carpets that were in the house when we bought it. That helped a lot!!! The previous owner loved poipourri, and I think the walls and carpets would coated with the stuff!

Here's another approach...........you could have reflux.
Some of us have stomach acid that comes up into our throats.....especially when we lay down. You might not even be aware of it happening. It can cause coughing, hoarseness, sinus problems and I imagine even sneezing.
I might be really off here, but why not do what those of us with GERD do, for at least a couple weeks: Never eat 4 hours before lying down. Raise the head of your bed 6".
Avoid leaning over for extended periods of time. Avoid reflux producing foods (tomatoes, juices, chocolate, etc.).
And start out by trying some OTC acid reducers like pepcid or prilosec. Pepcid didn't work well for me, but a prescription PPI (proton pump inhibitor) did.
You could have reflux without having heartburn. I know this probably sounds far-fetched to you......but reflux can cause some pretty funky symptoms. Give it a try for a week or 2, and see if it helps. Reflux can cause all sorts of throat and ear problems.

Also.......I'm sure by now you've kept a food diary.....but just in case you haven't, give that a try too. You might be sensitive to something hidden in some foods you eat.

And also be sure it isn't from another med you are on (or a vitamin supplement, etc.).

I thought about the GERD too. But the sneezing points more to an inhaled irritant. Of course, it's possible that the poster could be suffering from both.

I wondered also about the inhaler. I have allergic bronchitis and I cannot use inhalers. They make me cough until I feel as if I will explode!! I hate to suggest that you ignore your doctor, but I would be tempted to quit using the inhaler for about a week after you get the house as dust free as possible. See if you can tell the difference.

Everyone is bothered by inhaling an irritant like pepper. Others can't handle cinnamon or other herbs. So many of our common household things have ingredients like that.....soaps, after shave lotions, hand lotion....we live in a smell-good society and I think that some of us have to pay the price for doing so.

And if someone in the house smokes......feel free to hit them with something hard and heavy. LOL

Get your teeth and allergies checked..cavities can cause sinus probs..and dust mite allergy, which I have, can play havoc..I have to vacuum my pillows and mattress regularly, and of course carpets and launder bedding in warm to hot water. Brush teeth regularly, including tongue and back of throat. For viral or other, 1t finely grated fresh ginger, in a little cold water and fill mug with hot water and sip (no sugar!!)..It's like hot ginger beer and does wonders