The reason that you resigned from your job could affect whether you should begin receiving indemnity benefits. If you had to quit because of your injury, you could be entitled to get your benefits restarted. Even if you quit for other reasons, you should be able to get indemnity benefits restarted if you can demonstrate that the work restrictions from your injury are preventing you from finding work elsewhere. Finally, if you are taken completely out of work, then you should be able to get indemnity benefits.
I am assuming that you have a Georgia Workers' Compensation claim and my comments above are based on that. The reason why I ask is that you mention the insurance compay's doctor in Iowa. If your claim is not a Georgia claim, the answer could certainly be different.
I agree with Jason. I recently had a client in a similar situation, so I got his doctor to agree that the current restrictions stemmed from the injury and should have been in place since the injury (i.e., for your situation, the "company doctor in Iowa" was wrong). I recommend you do the same.