SOLVED. A teenager girl that travels back in time/ fantasy. [s]

[Andreea]

Hi , i read this book when i was 14 meaning kinda 4y ago and I total forgot the title or how the cover might look like , please help me find how this book is called .
It was about a teen girl who was living in london if i am not mistaken where he lived with her mom , sister and grandma , he was telling about how once he got a really bad cold , since then everytime her head hurts and feels like fainting he travels back in time , I don’t remember to much about the action but she meets there a boy about her age , and ends up stabbed in there . If i am not wrong she had a mission where she had to steal something by attending a party and they get her ready on a tower where she there finds something disturbing about her mother (all this happening in the past)

[Kimberlyn]

Maybe Ruby red by Kerstin Gier?

[Andreea]

I believe it was this one , thank you!!

[Rainbowheart]

Ruby Red for the trackable link.