It is quite likely that you are having thyroiditis or infection of the thyroid gland again.
Such infections can be bacterial or viral.
But most commonly, thyroiditis occurs due to autoimmune causes, ie, for some unknown reason the body itself starts making anti-thyroid antibodies and these cause inflammation of the thyroid gland.
The swelling can then press on the trachea and cause breathing difficulties.
Steroids will solve the problem only symptomatically.
Since you are having a recurrence, you should consult a specialist for this - an ENT or Endocrinologist. You can discuss this with your doctor.
You need tests to detect autoimmune disease like a full thyroid profile, anti -TPO and anti -Thyroglobulin tests. Also FNAC of the gland and Ultrasound to find the extent of the gland.
This can detect the cause for you.
Treatment is with steroids and also according to the cause.
Consult your GP and discuss these issues.
Hopefully this will solve your problem. I do hope I was able to help you in resolving this issue. If you need more help, please let me know so l can continue to assist you.
Thank you and I wish you the best of health - stay safe!
Dr. P. Jyoti