Lost access to my MM account after today's app update

I was using a guest account on my iPad because another family member's Apple ID is logged in, and I didn't want to tie it to their Apple ID. I have been working on this account very hard, and have made in-app purchases with real money, and also happen to be the commissioner of an active league with 18 players.

Today's mandatory app update completely lost me. By the time my app was reinstalled, I was logged out, and the Guest Login now automatically logs me into the account associated with the Apple ID, which is a different account. No matter which button I click, I can no longer find my account. I am completely devastated. How do I regain access to my account?