Just record keeping first, you profile show you as a male.
Now to the part I can't answer, but can sympathize with, congestion. It sounds like your problem is both congestion an drip, right? I have just congestion myself, but enough to interfere with my sleep.
From a first reading the I note with specific interest the following.
Nasal spray twice a day - what type? Afirin and that type can not be used every day, they can cause a worsening of the condition.
Saline spray, I use that and also use a netipot irrigation. Here I note only to not use tap water for the irrigation - I used distilled water. These two use together have not solved my congestion, but I think they have help some.
Steroids never cure, I believe.
Maryland, this looks like a real lead. Were you near the sea? What was different? What time of year? If you were inside a lot, then what kine of heat, cooling, furnishings, and so on... look for a reason you were better.
You have had more medical attention than I, I have only discussed my condition with my primary care who prescribed a nasal spray that I can use twice a day (every 12 hours) but it helps only a little. In my case my problem is clearly sinus swelling related, and isn't much of a problem when I am up, sitting or standing, standing/walking most relief for me. Does you physical activity have any affect? Back to Maryland, were you more physically active while there?