I think I would let him know that you are considering taking the art work out of his office and I would point out that you are planning to have your work displayed at a gallery in the near future. The art work is yours and I would imagine it is on loan to the office and you didn't "gift or sell" it to the office. I would certainly discuss it in mediation.
I would also consider retaining my own healthcare provider. I certainly wouldn't want him to have any knowledge of issues dealing with my health, if they should come up in the future. But, that's my opinion. I would certainly encourage you to look around before saying anything about changing up.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
