Since thyroid disease does not discriminate, thyroid blood tests can be run on any age child. You should talk to you pediatrician. Malfunctioning thyroid can cause growth and development issues.
I need to know the youngest age that a thyroid test can be done I have a 2 1/2 year that I think has and overactive thyroid
As soon as your thyroid develeps you can have problems. (even before you are born).
What type of symtoms are you haveing? mental issues to the point you feel crazy are just one of the many varied symptoms of thyroid issues (as well as symptoms of other things.)
Off topic - I was diagnosed many years ago as D.I.D (dissositive identity disorder) do a search on that and see if the symptoms fit.
Just being a growing teen in this nutty world can make you feel like you have split personalities.
But no matter the cause, I can hear the need for answers in your questions. Do you have access/ means to go to the doctor and have a check up?
peace be the journey
Paja