Have you tried Zilla Shed Ease? It's available at most chain pet stores and has really helped with a couple of bad sheds I've had - usually if a snake sheds shortly after getting it from the breeder or the time when I pity-purchased a BP from PetSmart with really bad stuck shed.
Once you are able to get the shed off you can work on maintaining humidity to hopefully avoid the headache in the future.
Sorry just read better and saw your humidity is great. Are you measuring it with a digital hygrometer or the stick on kind?