Hello and thanks for query.

Herpangina is a viral infection which causes ulcers in the mouth and produces fever, headache, and sore throat causing symptoms like painful swallowing.

Since it is a viral infection, it gets cleared in 5 to 7 days.

The sore throat which you are having now doesn't appear to be herpangina as it doesn't reattack within a month.

Your sore throat could be due to streptococcal infection, the commonest infection causing sore throat.

You must consult your doctor for the diagnosis which can be done by throat swab culture and take appropriate antibiotics for it.

I hope to have answered your query however you can revert to me for any further query.

Thanks and best of luck.

---

Hello
Although thyroid disorders don't cause ulcer but celiac disease can cause ulcers in mouth.
Other causes of ulcer may include
Slipping of toothbrush inside and hurting your throat
Lack of iron or vitamins like B12 or FOLIC acid.
Some females get it just before their periods
Oral thrush
Leucoplakia
Use of anti inflammatory drugs etc

Generally these ulcers heal of their own by home remedies like
Taking vitamins
Saline gargles
Using mouthwashes like chlorhexidine
If these ulcers don't heal in three weeks then you must consult your doctor for proper examination and investigations as this could mean some serious underlying disorder.
Thanks
Regards

---