That happened with me because I have a hiatal hernia so when I burped it would be stomach acid among other things. Not only did it taste/smell terrible but it did burn.
As for the swollen areas, are you having difficulty passing gas or using the restroom in general? You may have an obstruction of sorts. Anyway, it's good that you're going in and having things looked at! I hope they find out what is going on soon so you can start feeling better.
20 years old, Diagnosed with moderate to severe Crohn's and Colitis in May of 2008.
Prednisone 20 mg, pentasa 2 pills 4x a day, bentyl as needed, omeprazole in the morning, multivitamin, humira every other week, and good probiotics.
Surgery for ectopic pregnancy most likely the result of severe Crohn's inflammation in July of 2008.
Attempting a diet without refined sugars, high fat content, bleached or bromated flour, most dairy, red meat, and avoiding anything spicy like the plague. Also refuse to eat anything with trans fat or high fructose/corn syrup.
"He who has a why to live for can bear with almost any how."