Hi, Dewey. A Structural Engineer is what you want. I don't know where you are located but I would start by checking your list of friends for an architect or call one of the Architecture Departments at a nearby university to see if they will suggest one to contact. Of course, you always have the good old phone book.
Certainly you will want to save as much on this as possible and still get a good job. One way that you can do this is to have all the plans and drawings that you can find for your house available. Check your city hall. Having pictures or video tapes made up will help quite a bit too. The engineer is going to want to do his homework before he makes comments and making this as easy for him as possible will help both of you.