Black marks on bedroom wall

Firsttime2021

Hi just after some advice 

we bought our house that we rented from
my parents back in June, they bought the house in may 2015 a complete new roof was put on. Over the summer this year when it’s rained these back marks appear. I’ve had a builder in who said the brick work on the outside needed repointing. That was done.

the marks continued to come back I had a roofer come and have a look who actually worked on the refit of the roof back in 2015 and he said there was a big crack on some brick work surrounding the chimney above this room. He checked the roof and said it’s just the big crack and This was repointed last Friday.

again today we’ve had rain. And the marks appear again. 

This room has 3 external walls to it and there are only marks on two of them 

Who do I get in now to have a look? Any advice would be greatly received thanks 

Bendy_House

Do you have access to the roof/loft space? Are you able to crawl towards that eaves with a bright torch?

(Although that has surely already been done.)

Could you post a photo of the corresponding outside? Try and tie up the inside and outside photos.