Hi Hobart! I understand your bewilderment, and also have a DX of CFS, which has taken me a couple of years to accept and adapt to. It's a horrid DX, mainly because it's so poorly understood, especially by medics and support systems who should be there to help!
I don't know how much you know about CFS as I imagine as it wasn't the diagnosis you were expecting, you may not have had a chance to read up yet. Muscle pain, neurological symptoms and extreme debilitising fatigue are common symptoms, along with a whole host of other nasties. The trouble with CFS IMHO is that is is also a DX of exclusion, the it doesn't fit the DX for x,y,z, therefore this is the only thing left! CFS has similarities with MS and SLE and all sorts of other autoimmune and neurological conditions but as yet there are no commonly used lab tests to say definitively that it is the correct DX, - the only tests that are done are to rule out other better understood conditions, for which there are tests. MS for example has a very clear set of diagnostic criteria now( although in the days before MRIs it was more symptom driven) so there can now be years between first symptoms and the definitive test signs being detected, leaving years of undiagnosed and untreated limbo. Very frustrating. This applies to several other autoimmune conditions too. Some people dxed with CFS by exclusion go on to fit the criteria for other conditions, and then get the right treatment for that condition. CFS has only symptomatic treatment.
Any way back to CFS. I had the same disbelief! There are a few books on the subject but some are very depressing just because they are so unhelpful. There is however hope. I am a lot less unwell than when I first got sick.
The other thing you mentioned was your back. Could spinal compression be causing some of your symptoms perhaps? I am not a medic so just speaking from my own experience, and also have spinal problems, so it rang a bell with me.
We have a supportive thread (about spoons) for people with debilitating conditions, which you may like to join. There are others with newly diagnosed conditions.