Can you go back and question your doctor's rating? Only if you want to infuriate him. Not recommended. You should get a free consultation from a local workers' comp lawyer. The lawyer may be able to explain your alternatives under Tenn law.
This answer is intended as general information and not as specific legal advice. If you want to have a free consultation with me, please contact me through AVVO.
I suggest you talk to a tenn attorney however if you really feel the testing is incorrect you can ask the physician to be retested ( which they probably won't do) or take your chances with an ime. See what a tenn atty thinks because each state is different
Injured workers disagree with their WPI/Recovery about 2/3 of the time, and everyone thinks that their situation is different. Each situation IS different, but unless the perceived error is in the 5% outliers of the statistical Bell Curve, the system does not really have resources to stop the train. Your Attorney can attempt to question the findings, but significant change is highly unusual.
We offer general concepts, but you should give ALL your facts to a licensed Attorney in your state before you RELY upon any legal advice.