Ball Python Burrowing

Your uth needs to be regulated by a thermostat. If you have that set to 90 then you should be fine to turn off the heat lamp to check what the enclosures temp drops to with just the uth.

Definitely get a thermostat to regulate ALL your heat sources. If you are in a pinch, Jumpstart is a good budget friendly starter thermostat, but is an on/off style. Consider them a decent place holder until you can upgrade.

https://www.amazon.com/MTPRTC-Contro...art+thermostat

Ideally you’d want a proportional, high quality one such as Herpstats (the best) or Vivarium Electronics.

https://www.spyderrobotics.com/index...=index&cPath=1
http://www.reptilebasics.com/thermostats

I have a vivarium electronics T-100. It monitors temp and humidity via a wired sensor that gets placed in the tank where you choose. I move mine around to see the difference in my warm n cool sides.

Aside from that, I know my Ball does just about everything I could imagine it doing from burrowing when the substrate is soft enough, and climbing 2 feet high to the top of the tank to bask under a heat lamp. If you stay up one night before feeding time say a day or two before it's scheduled feeding you should notice it being more active looking for food, or just looking around.