For 2 yrs have had high potassium and low sodium and have hypothyroid but TSH levels okay with meds, what could be wrong?

Low Cortisol. Someone with one autoimmune condition (including most people with hypothyroidism) are at somewhat higher risk to have another autoimmune condition. One possibility here is addison's disease (adrenal failure), in which the antibodies attack the adrenals, causing low levels of cortisol and other adrenal hormones, which can result in high potassium & low sodium.
Adrenal fatigue. You could have adrenal fatigue also. Tsh fairly useless test. Check free t4, free t3 (liothyronine), (liothyronine) and reverse t3 (liothyronine).