I feel my heart pounding, I feel him moving ...

I feel my heart pounding. In fact, I feel him stirring hard. A very uncomfortable business. Sometimes it feels like I've had a big fright. As I lie down, it looks like it gets worse. Sometimes I wake up in the middle of the night as if I'm dying, my heart racing and half disoriented. I've done a lot of exams and, thank God, I've never given anything. But what to do with this situation? What would that be? Use daily PURAN T4, 125mg, for having done total thyroidectomy, because of a carcinoma. Thank you for a possible response.