Hi op
firstly il say your anxiety surrounding your thyroid issue is exasperated by having an over active thyroid as it speeds up metabolism and Adrenalin which is also what causes the palpitations and heart rate spikes.
I developed a sudden over active thyroid over ten years ago now and was exactly like yourself.
mine escalated due to my body not tolerating the meds they gave me to slow it down so I opted for a removal as I really was unwell and hospitalised with it.
my levels were however 8 times over the highest level which was absolutely 😟
after removal I have been on thyroxine and have had the odd blood test that was reading slightly under but then would have one that would read over.
the shortness of breath is common as well as the palpitations and heat panic as I call it.
as your losing weight your body doesn’t need so much thyroxine so it will take a little while to stabilise.
all I can recommend is to be patient as it will slow and the racing heart and panic will settle down,but in the mean time I used breathing exercises,I did yoga to calm my mind just at home for ten minutes in the evenings, and really try and lower rushing around and juggling too much mentally.
we really don’t realise how stress affects the body which will be making your symptoms worse.
I know you say your not stressed but this is making you anxious and your posts sound so like my brain works when I’m overactive so try and slow it down
i I find if I watch easy watching feel good films in the evening it settles me better.
also sleep with a fan because the Adrenalin spikes create hot flashes which send you into a panic.