I can chime in on both the HIDA scan and dapsone. We must be two peas in a pod!
I also had a HIDA scan completed back in May due to extreme pain in the area of my gallbladder. Doctors were certain that I would have to have my gallbladder removed (this was before I knew I had lyme and co). My scan came back normal, to everyone's surprise. It wasn't until a few months later that my LLMD told me that he's had many bartonella patients lose their gallbladder and/or appendix b/c doctors thought that was the issue only to find out that it was not and it was the bartonella attacking them the entire time.
When I first started treatment, my first LLMD was on a Dr. H high and put me on dapsone right away. I herxed VERY hard on just 25 mg of it and my platelet counts went down just being on it less than a week. I really had a hard time with that drug. I just got off of bactrim DS after being on it for a couple of months and handled that one better than the dapsone. If you have an issue with bactrim I would caution you to be very careful with the dapsone. Start slowly and get bloodwork frequently. If you are allergic or have problems with sulfa drugs, I'm not certain why they would put you on dapsone to be honest.
All of this being said...everyone is different. You may not have as much of an issue with the dapsone. Many people are able to handle it and have great results. My other doctor said that she had people in two boats...some that were experiencing great success with it and others that were literally turning yellow from liver issues and getting anemic.
Go slow, keep up with the bloodwork, and communicate regularly with your doctor. I hope that it works for you!