Low thyroid falls into two categories: A disease, and non-disease form.
If you are found have a high TSH it can be from under active thyroid, commonly called hypothyroid (not a disease, its a condition), or from the autoimmune, antibody based Hashimotos disease. Treatment is mostly the same, causes are different in nature. Hashimoto is forever, while regular under active thyroid is sometimes temporary and can even be caused by internal body infections, heavy metal poisoning, other diseases, even pregnancy as the thyroid is a very weak gland.
You really need to have further blood testing for thyroid hormone levels, as these generally correlate with TSH levels. Free T3 and Free t4 are the thyroid hormones levels that need checking. T4 is commonly referred to as the 'storage' hormone that should be converted efficiently by the liver into T3, the 'consumable' hormone that every cell needs.
The next blood test is for thyroid antibody testing to confirm or rule out Hashimotos disease. In this case antibodies attack the thyroid gland , destructing it more every year causing the rise in TSH from the lowering of thyroid hormone output from the gland. This is a reason TSH rises and the prescribed thyroid replacement hormone needs to be monitored to offset the thyroid glands fluctuating or lowered hormone production.
Not everyone with under active thyroid has thyroid nodules, its more common in Hashimoto patients. Even people with no thyroid issues occasionally have thyroid nodules. If these are found, it is suggestive practice to monitor accordingly every 12 to 18 months via thyroid ultrasound.
Hopefully this will help you understand this better.
Do you mean "Thyrodox?" Thyrodox is not a prescription medicine, but a combination of vitamins and anti-oxidents that sometimes help those with both hyper and hypothyroidic symptoms.
Thyroid disease, in my opinion, is the unspoken epidemic this nation faces. I have founded the National Thyroid Foundation and written a book about 51 years of suffering with thyroid disease and at least 100 misdiagnosises. I have learned that hypothyroidism is very common in women once they approach 40 and beyond, and that almost 1 in every 10 white women will have thyroid disease before they are 55.
A jump in short period of time to 9.3 on your TSH should have been an automatic signal for your physician to order an immediate ultrasound of your gland to find out if nodules, cysts, or tumors exist, if the gland is growing or shrinking, and a look at your corrated artery right next to the gland to learn whether you are at risk for hardening of the arteries, and/or heart disease.
The reason for the rise is unknown in medical science. There is no cure for thyroid disease, only surgery/radiation, and chemical supplements.
A key point I did not read about in your note was how YOU FEEL? That is critical now for going forward. Best.