Can anyone explain why I was sent for a pelvic exam at rheumatology app please

[anyhelpwith]

Had massive pain in my fingers and wrist since I gave birth 7 months ago. Finally got referred to rheumatologist who doesn't think it's RA, luckily. I've explained how my ankles always hurt too like I've been on them all day. Explained about neck pain I get and why I'm on cocodamol for a herniated disc.

He sent me for a pelvic exam to have a closer look at my sacroilliac joint due to ongoing pain in that area (been going on nearly ten years since pregnancy of first child) I'm just confused why the interest in my back if it's clear it's being caused by a herniated disc on my lumbar spine.
Would anyone know ?
He is going to X-ray my ankles and akylese heels too, he said this is because of my family history of psoriasis (I don't have it but my sister is covered head to toe)

Sorry if I sound really stupid but nothing was really explained and I'm now thinking about it and was hoping anyone with experience might be able to help me understand

Thanks

My x rays are generally normal (other than one of my knees) and it doesn't mean anything other than my joints haven't yet been permanently damaged by the arthritis. It's not changed the way I have been treated in terms of meds but does mean that I don't have to consider joint replacements at all at the moment.

Good tips thank you, I tend to go blank in front of doctors so I would probably just accept it if he says there is nothing showing, and then feel like a fraud !

I'm pretty sure he said ultrasound of my hands and X-ray of my ankles and Achilles heels... I'm guessing to expect a letter through for them though.
I got the pelvis X-ray literally straight after the appointment due to it being a quiet minor injuries hospital so that was good. I thought I'd have maybe had a call about it today but I've heard nothing so maybe there isn't anything significant to see ?!

write down any questions you have before your appointment and check you asked them all before you leave. I‘be been qualified for 30 years and still do this.