The Thermostat probe should be outside the enclosure, directly touching the heat source. Usually the easiest way is to put it between the heat pad and enclosure. Then your thermometer or temp gun readings should be taken inside the enclosure.
Don't feed again for 14-21 days. This should give you enough time to get the temps fixed and you snake time to recover and adjust.
what are the dimensions of your tub and what size UTH are you using?