Hello. Hoping someone could help. Have a 10 year old roof that is leaking . Previous roof was cedar and replaced with asphalt. Have a leak right under where the roof meets the sidewall . Had the roofer out and he said to caulk the window above which I did and still leaking. The water appears in the ceiling below directly under and along the sidewall or where the roof meets it. Any ideas and also how could I test to determine source of leak?