Hi Crista -- I've been fortunate to never have a problem with squash borers myself, but yes, that does sound like what you are dealing with. If it's not too late for the part of your plant that is dying, you can try burying the stem at several of the leaf joints in the dirt and it will grow new roots there. I suspect the squash are shriveling because they aren't getting any source of hydration through the stems that are withering.
Here's a link to an article on the University of Minnesota Extension website with a lot of good information about these troublesome pests -- I hope you have success in controlling them!
http://www.extension.umn.edu/d...
