Congratulations. Just as it is rare for people to win the lottery, it is rare for lawyers to encounter such people. I have never heard of a "specialist", and think you will have to search for lawyers with a more general practice.
You should consult a financial planner, not necessarily an attorney, or a trust and estates legal practice attorney. They can assist in planning for your future. If you already accepted the money personally I am not sure you can do anything to change the taxable consequences. Good luck.
Congratulations, as you may be aware suddenly receiving a large sum of money can indeed ruin relationships and destroy lives but we all buy those lottery tickets don't we? When you receive an annuity that means you will receive regular payments- either yearly, monthly, or biannually are common. This is done to allow a smaller amount of money to be invested up front to ultimately pay you the full amount you won over time. An attorney could assist you in planning strategies to protect the bulk of your money from others and yourself. For instance here in Florida we have a Constitutional provision that protects money invested in your primary residence or "Homestead". That is why some people claim OJ and many others buy an expensive "primary residence" in Florida to protect that money from creditors and judgment holders. So they can live in super-nice paid for beach homes even though they are totally bankrupt. This is one way to protect your assets from creditors. Other ways are creating trusts and keeping your possible liability low by conducting business under an LLC or Corporation. Setting up a solid legal plan for your future can cost you money but will keep you from being one of those rags to riches to rags stories that are all too common. You will need an attorney with experience in many areas of law real property or real estate, estate planning, and business law are a few. I suggest locating an attorney you trust that offers a general practice and has some experience with managing financial transactions such as yours.