Rita, you are ok. You may not feel ok, but you are.
What I said about the cancer and anxiety is only an example of understanding how bad you can feel. But that does not mean anxiety is worse than cancer. It is not. Cancer can end your life, anxiety cannot. No one has ever died from feeling anxious or even panic. It would not be one of the easiest to treat diagnosis's if it was so hard to get rid of. It only feels awful and that is what I was alluding to. I am sorry if I scared you. I should have been more clear.
You are hitting a spiral and talking yourself into being afraid. Don't go there. You may feel odd, anxious or different, but you are fine. I can tell from what you write and how you write that you are ok. There is nothing that is going to happen to you.
You are thinking ahead, loading yourself with anxious thoughts about the future, a future that is not here yet. You cannot predict the future. All you know is right now. Deal with now, let God deal with the rest.
The pendolol you are taking can cause excessive tiredness but it does not sedate you. It is a medication that lowers your blood pressure and a natural side effect is drowsiness. If you get some sleep, most of that will wear off.
Check in with your doctor about your thyroid symptoms and what is normal for you to experience. Thyroid problems can cause a variety of symptoms depending on your situation. Your doctor would know best what they are for you. But you can control how you react to them. You may feel fearful, but you are ok. What you have cannot hurt you. It is a feeling and that is all.
You are not starting at the beginning again. You have made progress and you will not go back. You may have a set back today but you can recover. And you will. Try challenging your worst thoughts. You have been through this before. And survived. You will get through this again.