We won’t be able to tell if it’s a burn or not without seeing it, but considering you don’t even have a thermometer for the tank I doubt you have a thermostat. Without a thermostat, if your snake doesn’t have a burn yet it for sure at a huge risk for one without a thermostat!
The thermostat controls the temperature of the heat pad so without it the glass can get very very hot.
Do you have any other heat source besides the heat pad? What kind of enclosure do you have? We will for sure need more info but from the sounds of it your snake might have an RI because of the wheezing and sneezing.
An RI is caused by the temps being to cold so if the heat pad is your only source of heat, then your ambient (air) temps are probably to cold for it (which is probably why it burrows down to get closer to the heat pad)
From the sounds of it you have some pretty serious husbandry issues that really need immediate fixing or your animal will be at risk. I would post a pic and a better description of your tank so that we can get a good idea of what all needs changing.
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