Have YOU contacted the insurance company? I would get on their website and start firing off emails to managers and the like.
I can see a MRI having to go thru channels, but not a CT scan. This is whats wrong with health care!
If you contacting the Ins co doesn't work then...
My best advice is the next time you have pain...go directly to the ER. Tell them who your primary care physician is. They will likely order an ultrasound then then eventually a CT scan. Its not the most moral or correct way to do this, but it is an option.
Hope you feel better soon.

As I said above, sometimes the patient/customer is able to get faster action than the Physician (people the insurance company have to pay).