I had cure autoimune disease i am of 17years can my thyroidism and brain fog due to med can cure.how long i need to take med further?

Thyroiditis?: If you are referring to autoimmune thyroiditis ( hashimoto's disease)- this at first can cause an overactive thyroid ( hyperthyroidism) followed by decreased thyoid function ( hypothyroidism). You need to have your thyroid hormone levels balance to achieve balance. The medication may be need for a lifetime or the disease can resolve.