What can I do if the ER doctor puts me on light duty, but I'm in pain from my broken and crushed big toe?

I assume this is an on the job injury. You likely seeing the company doctor, which you are required to do. He works for the company, not for you. So there is likely nothing you can do about what this doctor did. However, you may see another doctor, if you go through the right steps. Go see an attorney that handles w.comp cases. Their fees are often paid by the employer, and this is not something you should do alone.