Also, have any of you had such specific antibody tests done that you know definitively that you either have Hashi's or Graves? I wasn't aware there was a specific test to tell.
Yeah...well there are tests...graves antibodies are IgG antibodies and along with the clinical picture (i.e. hyperthyroid, goiter, exophthalmos and pretibial myxedema) it can give a pretty accurate picture as to which one you have (Hashimoto's is usually hypothyroid). Also, Hashimoto's antibody tests are usually for antibodies against thyroglobulin and thyroid peroxidase, while the antibodies in Graves' are different--they don't attack the thyroid gland per se, but actually stimulate it.
There is a certain type of thryoiditis where you can go from being hyperthyroid to hypothyroid pretty quickly...this is subacute thyroiditis. What is thought to happen is that there is a viral infection of the thyroid gland, and it dumps all of its stores of thyroid hormone in to circulation. So you get hyperthyroid...but then what happens is (a lot of the time) these circulating thyroid hormones cause an immune reaction against the thyroid gland which actually injures it. So, after the person recovers from the thyroiditis and hyperthyroidism, the person goes hyPOthyroid for a few weeks.