Hello...From your history it seems you are on
thyroid medication. Thyroid disorders are known to cause palpitations. But there may be other reasons too like Anxiety, Anemia, excess tea/coffee, some heart disorder, drug induced etc.
Next Steps
For further evaluation of your condition get some basic tests like an ECG, CBC,
Thyroid profile done. Consult a (M.D Medicine) physician/ Cardiologist.
Health Tips
Avoid excess tea/coffee.
Take
Thyroid medication regularly under Physician guidance.