Sagging ceilings in 15'x14' bedroom.

I am presuming this is upstairs with only the loft area above ,ceiling joists are generally small timbers not really designed to carry any weight, could be a number of things plaster to heavy or storing heavy ,stuff in the loft causing your timbers to fail, but without looking its impossible to say if they have failed completely, while a suspended ceiling may cover it up it probably will not support it if it collapses sorry but think it probably needs removed. good luck Alex

I didn't spend 40 yrs of my life perfecting my trade to give it away for free

If it’s a Kath& plaster ceiling you have what they call a live ceiling ( plaster has come away from the laths ) this needs removing g it cannot be fixed it’s also heavy when it falls & can be dangerous as well as very dusty

As already stated could be a few things. However is it a lime ceiling or boards, is there a leak, or could be movement in the house putting boards under stress.