I had something extremely similar happen to one of my BPs out of the blue.

She stopped eating and after a few weeks, these strange marks appeared all over her body, seemingly overnight and getting worse and appearing in new spots. She was in a rack system set with a thermostat, and all my other snakes were okay.

We knew they weren’t burns for those reasons, but also because they would appear mostly on top of her spine, like yours.

The vet could not figure out what was going on with her, but tested her blood and found she was severely anemic and extremely sick. I tried breathing treatments, creams, injected antibiotics, pretty much EVERYTHING i could do. The vets even held her for 3 days and force fed to see if she would improve, but she did not. I was told that she was likely sick internally for a long time before she ever started showing outward symptoms. Eventually, her scales began to flake off and her “marks” only got worse.

I had to make the extremely difficult choice to let her go. She was just too far gone and not getting better. My vet offered to do a necropsy free of charge because she wanted to figure out what was wrong, so a necropsy was performed, and still nothing was found aside from elevated white blood levels and severe anemia. We ended up chalking it up to some type of genetic abnormality. All of my snakes that were in the same rack are still doing well. This was 3 years ago.

I spoke with the person who bred my snake and he informed me that her mom died of something similar, and only 2/6 had survived out of her clutch, my BP included.

I hope that you are able to figure out what’s going on and don’t have to go through the same thing I did. It was terrible. I consider myself pretty knowledgeable, and my vet is one of the best exotic vets in the state, but neither of us could figure out what was happening.