As just being diagnosed with thyroid problems, I would ask to have thyroid levels checked by your primary as well. Some of the symptoms you are experiencing, you can also experience with thyroid problems.
Contact your pharmacist or any pharmacist about any interactions, they are your best resource for this. If you get all your medications at the same place, they know what all you are taking and if they see an interaction problem, they won't fill the prescription but will call your doctor for an alternative. Although anxiety can cause what you are experiencing, I would follow up with a Cardiologist to be on the safe side and to put your mind at ease. I know how scary this is for you, and fear just adds to the anxiety. If you see a cardiologist and he tells you everything is fine, accept this and move on. Since you have had this often with no other problems, chances are it's anxiety. But see a specialist to be sure. Take care.