That said, that's one huge nodule. I'm no fan of surgery, but I might want that puppy out myself.
However, as MG said, the nodule is probably not hot and wouldn't explain the up/down nature of your symptoms. You never told us in either thread; are you taking levothyroxine or not? If you are, it doesn't sound as if it's being appropriately managed. If you're not, you should be, given the Hashi's diagnosis and fluctuating symptoms.