Hello, Most of your symptoms (insomnia, weight loss, high heart rate, dizziness, and even nausea) can be attributed to Hyperthyroidism. The treatment with Methimazole and the beta-blocker will ease the symptoms within a couple of weeks. About Hypokalemia, I can say that this condition usually results from vomiting, diarrhea, adrenal gland disorders, or use of diuretics. In rare cases, it can occur because someone is not getting enough potassium, in his diet. In your case, the real cause of Hypokalemia is not clear, for this reason, the potassium supplement is very important. Digestive problems and nausea can be related to your low potassium. Extreme nausea in a young girl with hyperthyroidism is not common. For this reason, in my opinion, all you can do is to continue with potassium supplement for some days and to take foods that are high in potassium like bananas, oranges, cantaloupe, apricots, and grapefruit. You must stay under medical assistance because hypokalemia can be dangerous. Other tips that can be helpful for you nausea are: Drink clear or ice-cold drinks, eat slowly and eat smaller, more frequent meals, Avoid fried, greasy, or sweet foods. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Elona Xhardo, Endocrinologist