My ball python is developing these skin lesions

[lemonpie1]

Not sure what a UTH is, but humidity is typically around 70%

[zina10]

UTH is Under Tank Heater.

If you turned up the heat lamp and the snake can get within a few inches, that can certainly cause cell damage resulting in scales blistering and dying off. Make sure they cannot get anywhere near close to the light or lay on anything that gets super heated by the light.

Get a thermometer with a probe, or better yet, a heat gun. Take the temperature that this wood under the light reaches. A snake on top of that wood is even closer to the light. You need to be able to make sure about the different temperature gradients in your setup.

You say snakes..do you have more then one in the same cage ? Or do you have similar setups for more then one?

[SDA]

The problem with using dirt from outside is it can harbor unwanted pathogens that can explode in closed conditions with two of the very things that make them grow: heat and humidity.

Whatever the root cause it definitely looks like it has become irritated or infected. If fungal, antibacterial ointment will do nothing to kill the infestation. You could try antifungal cream but I would not recommend it personally. A vet visit is worth the knowledge of what it is instead of just throwing remedies at it in the hope of finding a solution.

As you stated, it has come back and more numerous so please for your happiness and your snake's health, please get it checked by a vet.

[lemonpie1]

I got 2 as babies and I've kept them together since

[Starscream]

I got 2 as babies and I've kept them together since

They each need their own enclosures. It may appear that they are 'cuddling' in their hides, and it does look very cute, but this is actually a struggle for dominance. Whoever is closer to the heat source, if they are huddled over the heat source, is the dominant snake. This is stressful to both of your animals and will lead to higher chances of illnesses and possible injuries if they are not separated.

@ dirt from the outside -- this is only bad when you're not doing a bioactive setup. Bioactive setups are utilizing the bacteria in the soil to help support your insect clean-up-crew, and the CUC tends to get rid of the bad stuff after a cycle or two. But if you're not doing bioactive, something a bit more sterile is better, especially when your animals are injured. You can switch to some other kind of substrate later, but for now while your animal heals you'll probably want to go to paper towels.