Hashimoto's is diagnosed by combining findings, not one test: thyroid antibodies (TPO, sometimes thyroglobulin), thyroid function (TSH and free T4), symptoms, and often an ultrasound. A normal TSH does not rule it out, and a low-positive antibody is not always disease. Found early, before the gland is damaged, there is the best chance to protect it and feel better.
There is no single Hashimoto's diet, but a few moves have real evidence. Correct the nutrient gaps you can measure, like iron, selenium, and vitamin D. Get your iodine to the right level, which takes an assessment, not one test. And cut a food only for a real reason, like a positive celiac test or too much iodine. Assess first, then personalize.
Lyme disease shares key symptoms with fibromyalgia, multiple sclerosis, and chronic fatigue syndrome, so it can be mistaken for any of them. It is also over-diagnosed in people who do have one of those conditions. The honest answer is that Lyme is worth confirming or ruling out with a knowledgeable clinician, not assumed in either direction.