If I go to my current GP complaining of lower back pain & a lifelong “catch” in the lower back/pelvic region, and tell him of a previous GP’s guess of sacroiliac joint syndrome (which was never followed up upon with previous doctor due to change of insurance), and my current GP refers me to a Rheumatologist, am I being pointed in the right direction?
I only ask because I was fully expecting to be sent to an Orthopedic guy (or girl) 
I would have asked GP in person, but he faxed me a referral 3 days after my appointment, and getting answers after doctor’s appointments isn’t always easy.
Don’t know much about what a Rheumatologist does, aside from what Webster tells me…
IANAD…
Well, a rheumatologist can send you to an orthopedist if it turns out to be something he/she can’t treat.
There are a lot of arthritis variations, and I know of at least one that often presents in the lower back and pelvis before symptoms appear anywhere else (ankylosing spondylitis… my sister has it, though she actually had first symptoms in her legs, IIRC). It’s more likely to occur in women than men, and usually between the ages of 15-40 or so.
Obviously, that isn’t a diagnosis
From what I can tell from google, sacroiliac joint syndrome looks like it could be related to arthritis, which is mostly a field of inflammatory diseases. A rheumatologist would likely be a good person to go to for something like that.