Technically your are asking for someone to practice law without a license. You could cut to the chase and ask those who sent you the invitation how they got your name. Most likely at some time you purchased a product associated with people having back nerve problems and that info was sold to a third party by the credit card company. Always check the statement you receive that explains when your credit card company may share information and your whether you can opt out.
Technically, I am not asking for someone to practice law. I am asking how I can find out who or how this incitation cam to me and who leaked my name and address.