a few years ago there was a guy selling a large redfoot colony on kingsnake. i bought a trio of them and when i picked them up from delta dash i was thrilled b/c the females were bigger than i had thought in the pics. anyways...i got them home and looked at them closely and noticed they all had soft shells in the back where their hips would be and all in that area and inbetween the scutes kinda looked like shell rot or some fungus was there. i think they were being kept to moist for a few years. i know this may not be exactly what is happening in your case but i fixed it by letting them bask in the sun. it has worked in fixing some soft shell issues in some sulcatas a while back too. im not sure what part of the u.s. your in but if possible on a day where the sun is out and the temp. is right stick them outside if possible as much as possible. hope this helps!