I used to be on strictly Cytomel several years ago and it was 25 mcg and it didn't bother me at all (to the best of my memory). It didn't make any difference in the way I felt so we discontinued it. Apparently, the doc thinks I need T-4 and T-3 combo. I was taking both Synthroid and Cytomel so maybe that gave me the headache. I also experienced horrible anger problems, irritability big time, and sweating. It did last several days after discontinuation.
I still think it's my metabolism or something to do with the pituitary. I exercise, eat right, do everything right but still gain weight. It's very depressing!