I freaking hate my doctors office. I got send to a specialist for an ultrasound that they said wouldn't cost me anything, but guess what I own close to 450$ for it.
Sounds like an insurance issue I would call the insurance company first and ask if your doctor's office ran it and whether they let insurance know the doctor requested it
A lot of times you need a referral too for a specialist and it needs to be approved before you're seen 😕