FOR A WORK INJURY: If you want Treatment (and Disability time) ok'd by the Comp Insurer, you must use a doctor in the Comp Insurer's "network" ... known as the Medical Provider Network (MPN).
Almost all Comp Insurers have networks, but a couple don't. If your company's Comp Insurer doesn't have that Medical Provider Network, then the rules say the 'employer' gets to choose your Treating Doctor for the first 30 days after the injury.
14 days after the injury, you should receive a letter from the Comp Insurer showing you the Web Address for that insurer's MPN, and you should be able to get into that network of docs and try to find a good guy...
....trouble is, most of the guys on the MPN are NOT good guys. So do A LOT of homework on the MPN docs before you choose one. If you don't research the MPN doc, you could end up with a Doc 'in bed' with the insurance adjuster who won't ask for any helpful treatment for you.
...IF THE INSURER doesn't accept responsibility for your injury -- if you get a "DELAY" notice from the Adjuster -- then you can go to your own doc. There is $10,000 of liability for treatment when an Inurer fails to either accept or deny a claim.
Hope that clears up this wacky system just a little!!!