You may be able to diagnose and inspect any bad framing by using a "jacking post" and a bottle jack. This will also come in handy when replacing the framing. What I do in that regard is to make a "T" with 2x4 lumber, the top cross piece is long enough to span three ceiling joists (approximately 36"). The upright is long enough so that a bottle jack and plywood can be put underneath the upright for jacking. I also attach a diagonal brace from the upright to the top cross piece for stability.
Don't get too crazy by applying too much pressure with the jacking post. It's possible to detach the roof or separate the wall with one of these.
Good luck and, if you can, post up some photos for better advice.