Welcome to the community! And I too would like to pass along my sympathies for your Mom. I too have had these infections for a very long time (45 out of my 54 years - I was symptom free for 2 years not long ago, got reinfected) - although I have not had many rashes, other than from Bartonella.
My questions would be does she seem to have a 'sensitivity' to nearly everything? If so, this may be MCAD - Mast Cell Activation Disorder. If this is a possibility, this is the best site that you could go to for information, as this Dr. really knows what he's doing: mastcellresearch.com/what-is-mast-cell-activation-syndrome-mcas/
Was she tested for other possible infections - bacterial, viral, or protozoan? It's more common for more than just Lyme to be passed at the time of infection, than it is to not.
Keep asking questions and if you can bear with us asking questions, hopefully someone will spark a thought that will lead to something for your mom!!
Herb only treatment for Lyme & Bart ended 12/11 - no active symptoms for 2 yrs -Herb only treatment for Babesia ended 12/12www.healingwell.com/community/default.aspx?f=30&m=2977364
Had Lyme, Bart, Babs, RMSF, Ehrlichia, Myco, Anaplasmosis, EBV
New set of infections 8/2014 - still treating.
Come visit me: dogwoodtraditionals.freeforums.net/