More gray hair being stripped

I had my hair stripped after stylist went crazy blonde on my hair. My natural color is medium/dark brown hair. I had hair colored with medium brown color. After going to Mexico for vacation and swimming, stylist said I had a greenish hue to my hair color and daid to strip off hair color and start over. I have more geay hair now more than ever. Is this normal? How to go back to how hair was before going blonde?