This sounds a bit familiar to me too. I have started always believing that theres something wrong with my heart. it used to be worse when i lay down to sleep I would wake up suddenly really freaked and sweating. its especially bad of course when I have palpitations even though i know those aren't always a bad thing and actuallly are usally because of diet changes. I also hate it when my migraines change and i didn't change anything in my lifestyle that might cause it. it is hypochondria the fear that theres also something wrong with your health i live with this constantly. its a part of anxiety and i dont know where it comes from.