Yellowing Gray Hair

I am 50 years old and have left my gray hair out for about 4 years now. My hair style is short. My problem is that the hairdresser I had been going to gave me a relaxer on all my hair and even though she  put something on for the yellowing from the relaxer, as soon as I went home, the yellowing came back as soon as I washed my hair. I went back and she put something on it and again it started yellowing whne I wnet home and washed it. I have used several gray hair shampoees including Shimmering lights, Nexus - Shampoo for gray hair, etc. I also have been using a Chi with the biosilk, so I possibly have burned my hair as well. I have since been to two hairdresser's. One who cut what she said was my permed hair, but did not resolve my yellowing issue and a second one that said he was going to take care of the yellowing but has not. I really need help. I cannot afford to cut any more hair. Please help.

You need a violet-depositing shampoo, which you can buy at Sally's.

Thanks,

I'll head to Sally's tomorrow