Welcome to the GERD board! I'm sorry you're having heartburn problems!
I also have GERD and quit smoking a year ago .. my symptoms are worse than when I did smoke. I suspect stress has a lot to do with this; as non-smokers, we have to decide how to manage our stress without lighting up. And stress is a major heartburn trigger, as well as IBS, as I'm sure you know :)
The symptoms you're describing: bile, heartburn, lump in throat - they're all symptoms of GERD. Maybe the Zantac doesn't work as well anymore because you've grown a resistance to it? Do you have a gastroenterologist that you see regularly for your IBS? I'd suggest making an appointment to get on a different medication for your heartburn. Right now, I am taking Zegerid, a powder PPI, which is working very well (although I know everyone reacts differently).
I was diagnosed years ago as having IBS, as I'm prone to bouts of abdominal cramping and diarrhea, but my doctor says both ailments can be caused by GERD. I'm not sure if that's the same in your case.
Also, certain medications negate my acid medicine. I tried taking Wellbutrin to quit smoking a few years ago and had to stop, because I had non-stop heartburn and bile. So you have to take note of whether your symptoms get worse after starting a new medicine/vitamin.
Do you notice your heartburn gets worse after eating certain foods? I can offer a few helpful hints to help reduce the burn: Minimal chocolate & caffeine, drink lots of water, don't eat after 7, and try sleeping with 2 pillows.
I hope you feel better soon! Please keep us posted! :)