Hello and welcome to HealthcareMagic forum.
Which medication are you taking for your thyroid
problem? Are you also experiencing increased hair fall?? Greying of hair can occur due a variety of reasons, but since its not genetic in your case; it could be due to poor nutrition and minerals deficiency. Make sure that you consume a balanced diet with adequate intake of fruits and vegetables(including green leafy vegetables). Consult a dermatologist
if your problem persists.
Best wishes and regards.