Is sagging floors causing wall to ceiling seperation?

mlar1@comcast.n

I need to repair my mother's raised ranch. The problem is the 1/8" gap between the wall and ceiling in the bathroom and shared walls in that area.
There are no trusses, just rafters, so I know it is not truss lifting. I think that it has more to do with the "handy work" done when the bathroom was added during a reno.
I can see that the floor joists were hacked into to put in the plumbing for the stand up shower/toilet/sink. I'm pretty sure that that is causing it. I'm assuming (i haven't torn down the ceiling in the basement yet) that at least two or three joists have been compromised.
The damage is only in that portion of the house. That's why I assume it is the joists not in the attic or with the foundation.
Anyone with some insight could email me @ mlar1@comcast.net. That would be greatly appreciated. I do not want to have ann engineer come in if it can be avoided. (mom is on a fixed income and really worried about $)