I have a 'permanently' blocked nose. One nostril is always blocked even though I don't have a cold, excessive phlegm, or snot. What could be causing this?

Sounds like you have a deviated septum. You can have it corrected but it requires surgery. Go to your doctor first. EENT dr.

I've suffered with this problem as far back as i can remember. When trying to sleep, if i lie on my left side, the left nostril becomes blocked solid and visa versa with the right side. Neither do i have a sense of smell of any sort. No amount of nose blowing or nasal decongestant seemed to make any difference so about 3 years ago i reached the end of my tether and finally went to my GP.
He asked me if i'd tried blowing it? to which i answered "No, I'd never thought of that" with a slight hint of sarcasm in my voice. He tried prescribing otrivine (decongestant spray) which i told him i'd tried similar things for years with no success. But he was convinced that he knew best, so i went along with it. After another couple of months i returned with the problem unresolved, so he sent me to an ENT specialist. He shoved an endoscope up my nose and recommended i had a septumectomy and rhinoplasty. Which would involve a minor operation to straighten the septum as it was bent to one side and thin down the walls of the nasal passages using a laser.
I nervously went ahead with the op thinking it would be the end of my woes. But after a few months of easy breathing and actually being able to smell, i seem to be back where i started.
I'm thinking of going back to the specialist to see what the next step is, but i'm not convinced they really know what they're doing. I don't fancy going through another op unless i was sure that it would permanently solve the problem.
I have recently discovered a sea water spray available at the chemist which when squirted up each nostril does provide some relief, but again doesn't last very long.
Should the specialist provide any answers i'll be sure to let you know.

i have this too! dr. says its allergies... i think she doesn't know what she's talking about though... if it were allergies it'd be both nostrils, not always just the same one all the time. good luck to you!