Olga, call your local Children's hospital :
***********.dellchildrens.net/services_and_programs/
for thyroid issues you will need endocrinology department.
But for starters, you might call social workers who will find out for you if the hospital has any specially funded programs that would diagnose and treat "pro bono". Many places would. If anybody personally knows any doctors in the hospital, especially department chairs, it will help.
It is hard to imagine that this child did not get any care for thyroid problems -those are fairly straightforward most of the time... so maybe there is more to the issue..... and then you might need general pediatrics department. And since this hospital is teaching, they might admit this child , once again, pro bono, and have house staff care for her, with professors consulting - not a bad deal, either
good luck with this
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Happy New Year to all! Virtual hugs!