Welcome to healthcare Magic!
The sore throat
is unlikely to be due to thyroxine
You should get yourself examined by a physician about your throat.
The problem seems to be related to an infection of throat- viral/bacterial.
You should improve the oral health, brush twice a day and do chlorhexidine
mouth gargles thrice a day and avoid eating any edibles during ensuing 2 hours to ensure good germicidal effect of chlorhexidine; Do warm saline gargles after you take anything orally.
I hope the advise would be informative and useful for you.