What are your params? Do you have good circulation in the tank? When I first got my gymnothorax fimbriatus it was breathing heavily too. After about a day he started to respirate normally. The jerking the body do you mean just swimming around alot? Are there any other tank mates?
I need more info before I can help. Its probably just stress though. I always turn off the tank lights the first day so that they can feel safer and settle in somewhere.
Please refer to the new posting guidelines sticky for the disease and injury forum. Once you have provided the proper information, there are several of us who would love to help. Thank you.