Welcome to the club. I suffered a few years with horrible blocked nose.
Like you I couldn't quite point out when it started, but after a few month of suffering I went to see a specialist. Had endoscopinc surgery + middle turbinate reduction, costed me $ 4000!!!!!
But it didn't help. My specialist kept saying that I am allergic to dust mites and that's what's causing the congestion.
I can't tell you how much I spent on different natural and non natural meds, from dut mite protector sheets, covers, tons on nasal sprays, saline spray, you name it, nothing helped.
I used to live at the time in a very hot tropical and humid climate. So I decided to give it a go and went to visit some relatives for a few weeks (in Sydney)
And guess what, almost as soon as the plane took of I got better
After 2 weeks went back and it all started again. So wanted to be sure that it was really that hot humid horrible climate which cause the congestion and left for 2-3 month this time to Europe. Cold and dry. It was definately better, but not perfect, at night time I still had half side congested.
Now I no longer live in the tropical climate, moved a year ago.
I still have problems, it might never go away, but heaps better.
In you case, first of all If you have clear discharge you don't have infection! So you don't need antibiotics!
The reason why your nose is clearer when you exercise it's because during that time the blood vessels constrict, so can breat better, As soon as you stops they swell up again.
So what you need is to get an allergy test, to see if you are allergic to somethin in your area.
Don't hold your breath, they might not find anything, or even if they do, and treat it, it might not get rid of your congestion. But worth to give it a try.
You can buy saline sprays, or can make your own at home, it's not addictive, probably won't help, but again, it's cheap eough to try.
Most likely the lining of your nose is swollen, maybe from allergy.
I just ordered an infrared lamp, it might help to reduce the inflamation
If nothing helps, you will need to see an ENT, or GP, they'll send you for a CT scan. You could have a polyp, or deviated septum, in that case surgery can help.
In any case I strongy advise that try to move away for at least 2 weeks, to see if you get any better before you jump on the operating table and spend a fortune on surgeries which might not be necessary and might not even help.
Did you try steroid nasal sprays at all?
What have you been trying at all?
If the spray helps, ti's great, if not, you can get pseudoeffedrine tablets.
(original pseudofed). It's not really for long term use, but occasionally shouldn't be any problem. Check with your doctor.
And ask for a CT scan, so at least you know if you have something in your nose blocking the airway.
Hope something will help, cause I can't imagine anything worse that this.