My bet is, it is Graves Disease.
Get your Free T3 and Free T4 and TSH done ...along with thyroid antibody testing done.
Post them back here when you can.
Also get a checkup with a Cardiologist.
You will need a referral from your Doctor for this.
No I havent. Im still new at this.
Have you had thyroid bloodwork done? If so, do you know the results? Are you on thyroid meds?