Perpetually runny nose, all seasons, and it's not allergies. What is it?

I have a perpetually runny nose, in all seasons, mostly when I get a little chilly. So like in July, hot as h*ll, I'm not sick, but I step into an airconditioned room, nose starts running. And it's so bad that one of my biggest fears is to be somewhere and I forgot to bring my tissues in my pocket or purse. Seriously, I have nightmares about it. Allergy medicine doesn't work.