Suggest Treatment For Multi Nodular Goitre Behind Breast Bone

I am 45 yrs old and have been diagnosed with a multi-nodular goitre from around the age of 25, it is growing behind my breast bone. I have suffered with severe headaches for the last 10-15years and feel convinced there is a link with the Goitre, I ve never mentioned this to a doctor before but feel I know my body, when I experience the headaches( which I do take regular meds for amitriptyline)my throat feels tight and uncomfortable.