Liz1967
As you get older, your body changes and your thyroid requirements do also. Your symptoms are more typical of hypo but your labs indicate hyper. Everyone is different. I lost some weight, only ten pounds, but I felt like I was hypo when in reality I was hyper so you have to go by the labs. It seems unlikely but not impossible your “dead” thyroid would reactivate. That being said, thyroid cancer is treated by thyroidectomy not RAI because they have to be sure all the thyroid tissue is gone totally so it can happen that your thyroid is suddenly producing hormone. Your female hormone status could be changing too as you approach perimenopause. Maybe you stopped taking something that interfered with absorption, such as proton pump inhibitors. Hopefully your endo can sort it out.