Penny, It is pretty hard to visualize this without plans or actually seeing it, but it sounds to me like something is sagging, like a structural beam. When the inspector is there, see if you can get him/her to look in the basement to see what is holding up the structure in that area. There probably is a metal or solid wood beam somewhere close. Check to see if a plumber or electrician has cut or drilled thru the beam. On the first floor under this area, there should be a load bearing wall somewhere close. The problem is that it is impossible to tell from the outside of the wall what the structure inside the wall is like, but have him look at the walls in this area to see if it looks like there is any movement of the walls in that area.
Good luck and take lots of notes on what he says. Henry in MI