I have black patches on my tongue which were noticed 6-7 months back. I can observe four patches which are approximately 2cm*2cm. I have been a smoker but for the past one year my smoking has reduced drastically.. I smoke once every 2-3 weeks.. I also suffer from hypothyroidism which has never been under control.. My treatment consists of thyronorm 150 mcg tablets.. But because I couldn't control my thyroid levels I started consuming 2 tablets of 150 mcg each at a time. No other significant history. Please provide a solution. Thank you.