It seems as though the two shouldn't be connected, but through research, I have found that your diet can play a roll on both. As I have looked at hundreds of documents, sites, blogs, and forums, I couldn't tell you the exact things I have found, but I have seen numerous times mentioning of gallbladder problems due to a diet that also causes gerd problems. I believe in my most recent research, about different nutrients and lectins, there may be something that has to do with your body not getting the proper nutrients and you absorbing things that are not agreeing with your body. Lectins in plants, specifically grains, can cause havok on our bodies. I'm not trying to turn you away from grain based foods, but it is something to consider. You do not need carbs from grains for energy, you can get carbs from fruits and vegetables and our body is able to convert fat into energy as well. What I am proposing, is to try cuting grain based foods as well as processed foods for a couple weeks or so and see how that does. You may want to talk to your doctor about this first, especially if you are breastfeeding.
Don't quote me on this, but I think I remember reading something about if your body doesn't take in the proper nutrients, it can prevent your gallbladder from working correctly and the toxins in your body help with creating the gallstones. I'm not sure on the specifics but it is something worth looking into. I recommend doing some research on lectins in grains and phytic acid. I hope some of this information is helpful for you.