Welcome to the site.
This could be a big deal but it could also be an easy fix. I depends on what you find, so here's your home work.
1. Do an inspection of the foundation from the outside, look for anything that seems to be out of the norm, cracks, deteration and crumbling. Do the blocks look to be level thru the problem area? how much foundation can you see between the ground and the siding?
2. Do the floor joist land on this portion of the foundation or are they running the other way?
3. Do you have a sencond floor above or single level?
4. Type of roof over this area, peaked end (gable end) or the end of rafters and a gutter?
In the fifties, this should be a platform house where the floor is built and then the wall a built on top of that. For what ever reason the floor is sagging and the walls are well nailed together and are spaning the load over the problem area. It too will sag over time, so catching this asap is a good idea.
You are looking for damaged foundation, if not you will be looking for dry rot or termit damage. Good Luck.