Yes, take him to the emergency vet. As sad as it is to say, you should probably prepare yourself to lose him, which will not be your fault if it happens. The fact that he likely has slipped skin disease indicates that he was mistreated for a very long time before you got him. While I very much hope that you can help him get better, he may just not have the resources left that he would need to do so. Nixon's success with his rescued ball python was so remarkable because it is both HARD and rare to save them after that much mistreatment. Also, if at some point you choose to euthanize, even then you have done some good for this snake by saving him quite a bit of suffering. Just get him to a vet so you can make as informed of a decision as possible on how to proceed.