“Hyperparathyroidism” has to do with the parathyroid glands and not the actual thyroid gland.
I think the extra is a good plan and I would make sure you reach a blood level of 50ng/ml before looking for any other reasons for your symptoms. I believe, through my own experience, that Vitamin D has a profound affect on the thyroid or thyroid hormones. If after increasing your Vitamin D levels you still have issues I would highly recommend http://www.tiredthyroid.com.
Now that you found Vitamin D and are “postpartum” are you giving your baby any Vitamin D???