Those are actually pretty common symptoms of GERD, and, yes, they feel every bit as bad as you say.
With GERD you really have to avoid certain foods that will only aggravate your symptoms. If you have a smart doctor, the doctor should have given you a basic list of foods to avoid. Some of the more irritating foods for GERD are coffee, real tea (as in black, green or white--all coming from the same plant), tomatoes, citrus and mint. While most people call the herbal infusions "tea", these are actually more correctly called tisane, thus the explanation of what I meant by tea. If an herbal "tea" doesn't bother you, then it's probably fine, since it's likely a tisane. But, I noticed that not all tisane mixtures are fine, as they're still irritating. I noticed that red rooibos is still just as irritating to me as real tea is even though it doesn't have the tannic acid or the caffeine in it. Since so many people are using this red "tea" as a substitute for real "tea", it seemed worth mentioning.
Just so you know, it's okay to go ahead and use antacid tablets such as Tums or Rolaids (or store brand) in addition to your prescription proton pump inhibitor medication. If you decide to use a liquid, which I find to be more effective at times, try to find one that isn't mint. Sometimes it's really hard to find one that isn't mint, though. While the "cherry" flavored stuff doesn't taste a thing like cherries, I find it to be less irritating than the mint stuff. None of it tastes good, which is why those flavors are added. If you choose the easier option of the antacid tablets, avoid the mint or the citrus flavored ones. And, do make sure that you follow with a full glass of water. I've never seen the suggestion of drinking water on any of the labels, but that seems to help. And, there is nothing wrong with drinking more water with GERD.
If your symptoms continue to be this severe, you should definitely go back to see your doctor.
When you mentioned that your symptoms are on the left side, that isn't really unusual. It has to do with the anatomy of the stomach. I've had those exact symptoms before, so I know how miserable that feels. And, yes, I had that same swelling you're talking about. If your symptoms make you feel out of breath, which GERD can do, get some rest on days when you feel like this.
If no one told you to raise the head of your bed or try using a wedge shaped pillow, definitely try that. These special pillows can be bought at a medical supply place. I found I wasn't really able to sleep in the pillow, but it is worth a try, because the idea is to keep you raised up so the acid will stay down.
http://www.medhelp.org/posts/Digestive-Disorders---Gastroenterology/Raising-the-head-of-the-bed-for-GERD/show/228481
http://www.ehow.com/list_7332146_ways-raise-head-mattress.html
http://www.walmart.com/ip/RemedyT-82-1497-Acid-Reflux-Relief-Bed-Riser-System-by-RemedyT-2-PACK/28593532 This is just an example of what bed risers look like when used for GERD. I would still try the wedge pillow first.