It's a bit difficult to see from the pics, which are a bit fuzzy. However, from those and your description, it does sound like scale rot. Hopefully someone else can take a look at the photos and comment.
If it is scale rot, it's a fungal infection that's made worse by humid conditions. It's transmissable, so you need to keep a very close eye on your other snake and make sure you always wash your hands between handling each of them. Also make sure they never share any equipment like feeding tanks.
I've been there and this is what I did to get rid of the pesky stuff:
- Completely emptied and disinfected the tank and all its fittings and threw away the normal bedding (bark chips in my case).
- Stripped back the tank to absolute minimum fittings: newspaper substrate, one hide at the cool end, one hide at the warm end and a water bowl. Scale rot spores will stick to anything - you need a setup that's easy to keep spotlessly clean.
- Replaced the newapaper every day, disinfected and rinsed the viv and fittings every day, making sure that all were absolutely dry before putting the snake back (as you've seen, the fungus can flourish in damp conditions).
- Every other day, I wiped the snake over with Bettadine to kill any fungus that was present on her body. Don't know what you have that's equivalent in the US - hopefully someone else can advise.
It took several weeks of this treatment for the scale rot to clear, and it was some time after that before she ate.
It's a major pain in the butt to sort out, but it needn't be a major health issue for the snake if treated correctly for long enough.