My asphalt shingle roof (approximately 20 years old) leaks. This is the
roof over the first floor that covers the kitchen, BR closet and
bathroon. I have had leaks into all three rooms. I replaced the black
felt and 27 feet of shingles (linear) from the side of the second floor
wall outward about three feet. I installed new flashing up under the
old flashing and re-nailed it. I've used black roofing caulk as well as
elastomeric caulk and have slowed down the leaks but not stopped them.

Went back out two days ago and noticed the bottom corner of the windows
were rotted. Since it was about to rain, I caulked the corners and the
area under the windows. That almost stopped the bathroom leaks.

My question is, is there a temporary fix I can apply over the shingles
and the exposed flashing (6 inches) to act as a water barrier until next
spring?

I've looked into Koolseal's elastomeric roof coating but they say it
does not work for asphalt shingles.

Any suggestions? Thanks much.