Citrine is a fairly common stone (and such a beautiful one!)
You can meditate with the orb - think about your condition, and cup the orb in your hands; invite the stone to help you ease the thyroid condition, and picture yourself being whole, healed and happy
If you do this a few times a week, it should help! Crystals usually work slowly, but if you are consistent, you will find it does work. If you spend a lot of time at your altar, or usually sit near it, that will help too. Just having the crystals around us can help to speed healing (but hands on tends to be a stronger effect!)
That looks like a great orb to scry with, as well! So many swirls - lots of energy going on in that ball!
Here is some info on citrine; if you scroll down a bit, you will see the bit about healing physically with it.
citrine healing