First off, please get some type of thermostat for your UTH. People here seem to really like the Herpstats and Vivarium Electronics but even a very basic $30-50 model from another manufacturer will save you tons of trouble.

Second, I have to ask what you have chosen for your substrate and whether or not you have any of the screen top covered?

And, welcome to the forum and best of luck with your new pet.

P.S. pic may help with suggestions to fix your issues, or some sharp eyed members may catch things that don't seem like an issue but, will save you vet trips, money and a distressed animal.