Anyone of you familiar with breaking hair? My Chelsey used to have a gorgeous full coat, which looks like its breaking, i used to think it was due to the rubber bands i used on her, so i stopped using them, but its breaking all over her body now

Is she short of vitamins ? I am taking her to the vet this week for her shots and will ask her. I have them on Nutro Choice "Lamb & rice" i use the CC grooming system and the Dog's & Stuff shampoo, conditioner & detangler.
Any help is welcome as always
Mandy