Looks to me like there's either a beam or girder truss spanning from wall to wall, and the point load at the walls is too much for whatever is supporting it to handle. Possibly a local failure (sagging) of the top plate in the wall under the beam/girder truss? Just a guess based on photos. You'd need to get into ceiling space to have a look at those 2 spots. You should have a manhole access somewhere to get into roof space. Do it early in morning with this heat
Doesn't look related to the tile in valley gutter or water related.