increased TSH level and cortisol level 6 years after thyroidectomy

Hi, I am new to the group, but I have a question that I could really use some help with. I had a total thyroidectomy after thyroid cancer 6 years ago. After having normal levels with synthroid for 6 years I had my levels check a week ago because I have been feeling awful. My TSH level was 136 when it is supposed to be between .4 and 4.0!!!!! Plus, my cortisol level was 80 when the high end of the normal range is 50. The endo raised my synthroid from .175mcg to .250mcg to see if that would work. I also did a dexamethasone suppression test for the cortisol this morning. I am wondering if anyone has ever had their synthroid stop working, and if anyone has experience with raised cortisol levels. Any information would be greatly appreciated.