Welcome in H.C.M.
I read your problems and also think on your past medical history of thyroid surgery
, as you are having this problem in episodes so it appears to be a medical problem rather than ent. Anyhow in local throat there may be possibility of-
(1) Adehesions pressing the vessels
nodes may get enlarged and pressing the vessels of neck.
To rule out it through examination of throat and chest is must.