Pain in throat and chest. Possible gas?

[SaberSurfer]

I have this pain evey now and then, It occurs when I am going to Burp, I get this almost unbearable pain in my throat and chest like something is being built up, but I cannot burp. It passes away after 10 - 15 seconds.
It also hurts to swallow, it's like there's something physically in the way, but there is nothing to be seen.
Every now and then it also hurts a little to breathe.
It started occurring after I had this drank a pepsi that had almost gone flat.
I figured it was just gas pinned up in my throat at first, but it must be something else, cause that would've gone away after a few hours, wouldn't it?
It's been over about a day and a half now.
I am a smoker, and that is a possible worry of mine.
Please Help.

[National Jewish]

You will need to see a doctor to find out the nature of the problem that is causing your symptoms.  The doctor may need to see you while you are having the pain.

[SaberSurfer]

That wouldn't be too hard seeing as I only gotta try and make myself burp.
Everything goes normally when I burp except when it reaches my throat everything brings up, and then it feels like this imense pressure building up for a sec or two.
The occurences of this is starting to subside more now, the pressure I feel from it doesn't seem to be as bad now, guess it must be disipating or something.
The worst thing now is that my throat seems to be somewhat sore.
It's still a little difficult to swallow but not so much as it was previously.
Either I'm not noticing it as much or it's getting better.

I've got an appointment with my Doctor in the morning tommorrow to check it out, but I'd probably be better of it by then.
What a health system we have here.

I hope this never happens again.