I too have been feeling unwell over the past few months and did not understand why I have recently asked my doctor to re assess my meds and do bloods, and yes there is a problem tho not sure what as yet as she changed my dosage for eltroxin , as i was already on anti depression tabs i couldn't understand why i was feeling depressed , get cramps in legs during the night, moody, and hot flushes when i am already on HRT, i went to doctor and said Hrt is not working i want stronger dose, you would have thought they may have said something about changed medication of thyroxin at that time but no i have never been told of change of formulation nor when they replaced original make of thyroxin tab i rang chemist and said they had given me wrong medicine even then nothing was explained... great medical system not!