Hello and thank you for using HCM.
I carefully read your question and I understand your concern. I will try to explain you something.
It is quite known in cardiology that thyroid gland problems might cause increased heart beats, or extra-sistolic beats that you feel like palpitations.
Usually, increased thyroid hormones or
hyperthyroidism can give such symptoms.
As you explain, You had a high
TSH level, meaning that your thyroid hormones are low and you take the medicine to correct this.
Low thyroid hormones or
Hypothyroidism does not cause heart palpitations.
So to give an explanation to your palpitations it is mandatory to know the levels of your thyroid hormones now. Maybe, increasing the doze of your medication might have alter the thyroid hormone levels.
So, if I was your treating doctor, I will firs ask to do your hormones, TSH, fT3 and FT4.
If all this are normal, i will ask a electrocardiogram, a cardiac echokardigraphy and of course a holter rhythm monitoring for 24 h to see that are this palpitations and how frequent.
Only after this chek up we can decide if it is necessary and how to treat your palpitations.
Hope I was helpful. Best regards.