I had to delve into this some myself, RH factors are ion channels on red blood cells. Mycoplasmas and Lyme, among other micro-vermin, like to live in RBCs. It would therefore make sense that they would be able to "turn off" an ion channel for something that made them less comfy in their new homes. How insidious! God I hate parasites!
wonko, my shoulders started to fall out of place when I was in the 9th grade, about three years after I feel I was infected. Whatever I have/had eats cartilage it appears. When I was in my early 30s, a chiropractor told me my lower disk looked like someone that was in their 80s. As some physicians don't believe in Lyme, I don't believe in autoimmune. The immune system, in my opinion, is trying to attack something and I don't mean self. Perhaps something small enough that it is inside the cell, like a mycoplasma, or the round form of Lyme.
I'm sorry that I don't know much specifically about Lyme and RH factor...I've read plenty of patient testimonials stating that Lyme caused back-and-forth positive/negative ANA results, which seems consistent with your positive-negative RH factor.
The things that consistently show up as abnormal on my blood work are SED rate and c-reactive protein (both inflammation markers), vitamin D (always low), and some borderline abnormal thyroid stuff (slightly high TSH, low positive for thyroid antibodies).
Do you have classic symptoms of rheumatoid arthritis? I know with RA the joints get really red and hot, and the joints start to erode, while Lyme arthritis tends to be less destructive.
As you probably know, RA, or any autoimmune condition, is often treated with immuno-regulating meds like steroids, which are a big NO for Lyme and infected patients.