Choclate can be poisonous to dogs. Call an emergency vet and ask what you cab give your dog to throw it all up and how much to give. I know its gross but it saved my dog. Better yet get him to the vet now they will probably tell you to bring him in anyway. good luck!
Don't wait to find out when it's too late ... It is common knowledge that chocolate is extremely toxic to dogs. Given the amount your dog consumed, I would definitely suggest to consult your vet. A death caused by toxic poisoning is slow and painful. Please get your dog help.