We got our son tested for bartonella thru Igenex. It came up negative, but our LLMD at the time (a researcher & teaching dr in Missouri) said there are at least a dozen forms of bart so it doesn't mean a whole lot.
My daughter also has bart & I realized it when we were doing swim lessons years ago because at the time she was still skinny as a twig & I noticed she had what looked like stretch marks on the backs of her legs. Like your son, my daughter had never been fat - nothing had stretched her skin so stretch marks was very obviously not the answer. Thankfully I had just found this forum & suspected it was a bart rash. That purplish to reddish striated rash is pretty distinctive. I'll post a pic of my son's rash on his leg (he's also never been fat & his skin has never been stretched out by anything), but if you google "bartonella rash" and click on images, you'll see a lot of pictures of them. That actually helped with my family's skepticism - seeing my pix of the bizarre rash proved to them that there really is something out of the ordinary physically going on with my kids & mainstream medicine has no clue how to deal with it.
I've looked at Buhner's protocols and felt the same sense of overwhelmed confusion so I'll continue watching this thread, too! Someone pointed me to Dr Zhang's book to learn more about his protocol, but a friend of mine just diagnosed with Lyme was telling me about Dr. Rawl's book "Unlocking Lyme" that she's reading. It all gets so confusing. If only there were pat, straightforward (affordable!) answers available.
FWIW, my son says that of all the things we've tried, lomatium (we get it as SEES-plus capsules from Barlow Herbal.com) has done the most to improve his symptoms. Fair warning, though, it can cause a rash initially which does go away after about a week but itches miserably in the meantime (ours was actually like german measles which made me wonder if it releases viruses - including vaccine viruses - sequestered in the body) so if you do decide to try it, be sure to follow their instructions about how to minimize that possible effect. I didn't pay enough attention to that (in fairness, my husband had gone into the hospital for an aneurysm during the time we had started), and because I didn't realize what was going on till it was fully upon us, we had to just ride it out. Which made for a pretty miserable week. Afterward though, my son said he felt like he could think clearly for the first time in years.