Callina, i know you meant well but that is misinformation. Nobody can ever diagnose a thyroid problem without doing a blood test. With mammals, yes, a goitre can suggest a thyroid problem but this is not common in amphibians.
With a puffy chin like that, there could be many different causes. I use the F.B.I system to rule out common causes. Foreign body impaction or reaction (such as a granuloma), bloat (which can be due to any metabolic disruption, kidney problem, heart or liver problem, toxins, starvation and yes very rarely endocrinological problem) or infectious stomatitis. You will need to do biochemistry on the blood samples to determine the cause.
More rarely, you get neoplasia or cancer. There is another benign cause. That is called obesity.
Nontheless, the bottom line is that if you want to pursue and investigate this further, a trip to the vet is necessary.