Hi I Had My Throws Removed Five Years Ago With

Hi I had my throws removed five years ago with radiation pill but prior to that I had AF due to hyperthyroidism and I had a cardiac inversion done and have since been on tambocor daily and warfarin and Eltroxin. Had my INR checked the other day and it was 1.4 so upped my warfarin.
However lately I feel I can feel my heartbeat aeration again and the feeling of it beating in my throat. No chest pains etc. I surf most days and am relatively fit so not sure what it could be. I was wondering if my thyroid had grown back