Q about thyroiditis and cyst in thyroid gland?

I have a 2.8 cm cyst in my left thyroid gland... also i had thyroiditis for awhile and been to like four diff doctors,, not one gave me a patient pamphlet or any info about it.. i found most of my info online.. my doc in springfield(100 miles from my house) first said he wanted to do surgery and just take out the left side of the thyroid and the cyst and the right side should start doing its thing by itslef.. and if he didnt take it out i could have no more probs but could get thyroiditis again and it could burn my whole thyroid out,.. now he is sayin that he just wants to do a biopsy of the cyst and make sure it is not malignent .. and if not just leave it be.. i am confused also my throid antibodies were all in normal range... so how did i have thyroiditis.. and what caused all this?? i have never had any problems with my thyroid before as far as i know.. so what is going on and what should i think?? please give me some info and let me know your thoughts.. thank you very much jess