Hi kaz...
How can you tell it is your oesophagus that it is hurting? Could it be a sore throat, from the start of a cold as Ange suggested maybe?
No idea what the headaches and sweat may be...that often happens when your blood sugar is low, but obviously if you are eating at the time, it isn't that....
At the end of the day, if it persists, see your doctor!