Our daughter was treated with plasmapheresis in 2017. She has pandas/Pans but not Lyme (we think?). She was typically treated adequately with antibiotics but for whatever reason we couldn’t get that one flare under control with abx or prednisone, so we went looking for ivig. ..
The immunologist we found had more success in his patients with plasmapheresis than ivig. Our daughter’s symptoms were severe at this point. It is also often easier to get insurance coverage for plasmapheresis than ivig, which is curious to me. For all these reasons, we went with plasmapheresis, and would do it again in a heartbeat. I cannot express how life-changing it was. (Two years out we may be needing it again, and if we do, I will be nothing but optimistic going into it.)
We are in VA so I don’t think I can help as far as who can treat near you. However, don’t take the “it’s impossible to get in CA” and just give up.... start making phone calls. Call area hospitals and ask if they do plasmapheresis at ALL, regardless of reason. Ask which immunologists order it. Work backwards from there. You are at an advantage because of your son’s age, as the issue is often finding an apheresis unit with the capability of treating a peds patient. Your son is not a peds patient so you already don’t have that barrier! I do not have experience with Lyme related to plasmapheresis. Also don’t take the “insurance won’t cover” without checking your plan on your own. You can call and ask if the cpt code is covered (I don’t have it in front of me but could find it) and whether it needs preauth. Don’t give up.
Hope I helped or at least gave hope. Good luck.