Lawyer emailed me and dropped my comp case

I had a attorney from 9-16 but he just emailed me to drop my case 3 days ago because he said the Dr said it was from a A Pre-Existing condition. I had surgery from this new injury which workman's comp has paid for but now Dr says I have to have total knee replacement and they say they are not responsible. I never received a panel of Dr's to choose from which comp is required to give me and they are now giving me a run around that they are not responsible. What do I do ? I now have no Lawyer which I was unware he was dropping me until the email and I have no idea What to do