We have a concrete tile roof - house built in 1983. The roof developed a leak
where the valley is. One of my neighbors was in the roofing business...he
explained it is common for this to happen after about 15 yrs., but that once
it's fixed there should be no further problem. They removed the tiles - at
least set them aside - and fixed the problem underneath. Then they replaced
the tiles and repainted. Perhaps you can do the same. Or, may be cheaper for
you to just get new roof. Don't know about repairs in attic.

Mine is okay so far.