Hi!
I had the same thing happen to me, my doctor, whom i loved retired. They tried to pawn me off to a Nurse Practitioner in his office since they are so busy, but i drove over 2 hours to see this doctor in particular (because he was so good) that i didn't feel it was worth my time and gas money to drive all that way for a NP (don't get me wrong, NP's can be great too, but the distance just did not justify it for me). I researched the other doctors in his group and called the office manager and told her the situation. They were happy to get me in with the doctor i wanted. My new doctor did end up meeting me and going over everything from scratch again and he did end up switching some of my medications around (not successfully though). Hopefully you will have a good transition.
Good luck!