I with those who say to get professional help. The link Sparky gave you has some great advice. Perhaps the following will give you some additional help. Before doing anything, please be sure to read the articles about cleaning. The second link is for a museum site and information about asking a question. I'm not sure if they can help but I think it is worth a shot. It is a beautiful quilt. Good luck.
http://antiques.about.com/library/weekly/aa101199.htm
http://nequiltmuseum.org/museum/library_questions.html