Thank you for your question. I understand your concern. According to you, your TSH level is 5.6 which is borderline. Usually for this level of TSH, I personally would not start you on levothyroxine that too 50 mcg/day. Usually TSH levels should be more than 10 to start on medications or the patient should have the characteristic symptoms of hypothyroidism to consider starting at a lower level of TSH. But whether the usage of levothyroxine caused your BPPV like symptoms cannot be conclusively said unless I can clinically examine you. And since your dizziness occurred when you turned to one side, another possibility to be kept in mind is the presence of cervical spondylosis, especially at your age. In your condition, levothyroxine may not be required though checking your thyroid function every 6 months would be a good idea. I would advise you to get a second opinion regarding you taking levothyroxine. You may also get tested for the presence of antibodies to thyroid gland which can lead to hypothyroidism in the future, though this is not necessary. And the fact that once you are on levothyroxine you have to take it for the rest of your life is not always right, as a number of causes of hypothyroidism are present. I hope i have helped to clear a few of your doubts, and I would be more than happy to clarify any further doubts if you can get back to me.