hi, the first thing you should do is go for a helico-bacter-pylori test to determine if your infected with this ulcer causing stomach inhabitant, burping for more than a couple of weeks is usually a first sign of this infection, its a simple breathe test, non-intrusive. good luck.
You may want to consider having an endoscope done. A few years ago i had one done because i was feeling as though i couldnt breathe or swallow and they had to go in and open my esophagas because it started closing. This can happen due to high acid or gerd. It helped me alot once it was done.