"For Underactive Autoimmune Hypoactive (Hashimoto's Thyroiditis) TPO and Tgab" Be sure to get the TPOab, not TPO test, as they aren't the same. TPO is an enzyme used to produce thyroid hormones; TPOab is testing for antibodies.
Your symptoms can actually be associated with both hyper and hypo, so you'd need proper testing (Free T3, Free T4 and TSH) to determine your status.
Have you been tested for vitamin B12 deficiency?
Do you have your latest thyroid lab test results? If not, request a copy from your MD, post the levels and reference ranges provided for each level here on the forum for advice and explanation of results. You say you are underactive but the twitching,shaking palpatations sound like you are experiencing both Hyper and Hypo symptoms, thyroid disease would also cause digestive issues. Are you on ant medication for thyroid? If so, what is the name of the medication and dosage amount. Without the above info, it is difficult to advise. If you have not been tested for thyroid disease, you should see your MD and request the following tests, For Underactive Autoimmune Hypoactive (Hashimoto's Thyroiditis) TPO and Tgab, For Overactive Autoimmune (Graves Disease) TSI - For thyroid hormones Free T3, Free T4 and TSH, The thyroid hormone Tests should be done regardless of previous diagnosis because you do need an adjustment of medication and these tests to determine dosage. Best Wishes FTB4