Help!

I just received a call that Dr. Shina will not accept CHA for follow-up appointments. I had Blue Cross during my surgery but the state changed their insurance to CHA in January. I don't know what to do. They said that I will have to pay out of pocket for the office visit. If you are a state employee and have had a the same thing happen to you, please let me know what you did to correct it. Thanks. Angie