micky wrote:

If it's the caulk, it's been there for 13 years. How come no drip into
the 2nd floor until this year?

What I see in that picture... weep holes are clear. It's the bad
caulking between shingles and flashing. All those gaps will let
water in. Where the roof is buckled, I see no caulking at all.

I would get someone up there to recaulk that line asap. Fix the
buckled part later if you want to wait. For now, stop the leaks.
Recaulk it and check the other side too.

Note: No caulking outside will hold up for 13 years. With an
important thing like a roof, get that caulking checked and
repaired once a year or two.