Suggest Treatment For Hypothyroidism Symptoms

I had Graves disease about 15 years ago . I was on medication for about two years and have been fine since. Now I am having symptoms of hypothyroidism. My symptoms are itchy skin but no rash. Mostly, face, neck, chest and sometimes legs. I have not changed the soap or shampoo. My diet has not changed. I also have had a slight weight gain in the past 6 months. Other symptoms are sleep problems. I fall asleep and wake up in four hours and have a hard time getting back to sleep. Sometimes I wake up in a sweat. Sometimes during the day, I have hot flashes. I am 76 years old. I do have arthritis of the hip and have noticed that sometimes the muscles in my legs seem weak. I try to walk everyday. My question is since I once had Hyperthyroidism, can I now have hypothyroidism. Thanks for any answers. Judy