How to fix this temperature issue?

[Tbs1417]

Thank you for your answer! I moved the probe outside of the tank and I am going to buy two of those digital thermometers that you mentioned! I did purchase an Exo Terra Night Heat Lamp 75 watt (I got the night one since the room he is in has natural light and I only needed the lamp to help the ambient temp.) Should I get another thermostat for the heat lamp to make sure it turns off once it gets to a certain point so he doesn’t get too hot? I read that a rheostat may be better for that. Will the lamp get too hot if left on without a thermostat/rheostat?