I also bet it was the rapid drop in your TSH. Keep a very close eye on it - the 137 may be too high for you. Do you have a BP cuff?
I went through this after my RAI last year - frightening! Good news (for me and hopefully for you) is after the TSH leveled out the BP went back to normal and I didn't have to take the beta blockers anymore.
Hope you feel better soon. Unfortunately I'm not one of the more experienced ones on this site. So hopefully you will here from one of them. Prayers Jessi
I am a person who goes from one extreme to another regarding TSH levels. I have gone from 9.2 to 0.13 in 1 1/2 months and there were times when my heart would start racing, and I felt like I was going to have my heart jump out of my chest. I do believe that your level drops do have something to do with your heart issues. I also have high blood pressure - even on blood pressure meds. I have been on blood pressure meds since my pregnancy 11 years ago. Never, ever stabilized after my PIH bought.