Excessively adding pages

I am working in a large document that was mostly cut and pasted from another document.

For some reason the document will randomly add blank pages to the document whenever I try to delete pages and if I add one page, it adds multiple pages. At onepoint it added over 3000 pages, until it ran out of memory. We took a look at the pages and it seems the header took up the entire page, and we couldn’t resize it. (I don’t know if that was relevant to the problem or not, but it was an observation.)

I also am having problems with a few of my styles not obeying commands (such as page break before) and some of them are not resetting when it comes to numbering. Is this connected to my other problem?

What can I do to fix this without losing my document?