This is a weird feeling, Usually occurs at night, it will start with a feeling as if saliva went down wrong pipe, like I got to cough, then when I Do cough.. it burs like acid AND I get this AWFUL smell, like bile when I exhale through my nose or when I cough.
The more I cough, the worse it gets.

That's actually common. Post nasal drip can burn, and when you cough, bile can come up.
But you can solve both. Post nasal drip solved with decongestants, LOTS of fluids (so that your nose runs, instead of that horrible glue collecting at the back), menthold cough drops when you lie down, and keep your head elevated, and make sure your bedding and pillows are clean in case you are allergic to mites. (Wash your pillow too.)

Bile is more work. You might want to talk to your doctor. It shouldn't come up so easily, and there are many reasons for it. Weak esophagus, too much bile production, acid reflux, problems with what you eat and drink. Avoid spices, caffeine, sodas, fried foods several hours before bedtime, have a bland dinner.

Well I DO get occasional Acid reflux, though. I'm not sure about the post nasal drip thing.. last time I got these feelings.. I thought maybe it was the little bit of bile from that went down the wrong way... and that caused both he burn.. and the smell.. but not this time.Its a REALLY bad smell. But its not my breath that stinks...

Bile does burn. And smell awful.

Post nasal drip isn't always obvious. I'm one of those people who gets a sore throat first, then I'm aware of the drip causing the sore throat, then I get the full blown cold or flu. Takes a few days for it to develop. But people with allergies (maybe you?) can have chronic post nasal drip with no congestion out the nose, and if it happens at night, I would suspect dust mites.

Just a thought. You know yourself best.