Kk21kk I'm sorry to hear about what your dad and yourself are going through. It feels like you're not getting clear information to understand why things are or aren't happening.
I haven't got experience with metastatic breast cancer but others will be able to provide their experience soon when they see your message.
In the mean time you could give the BCNA helpline a call on 1800 500 258 and they may be able to talk with you about what often happens or what to do next.
There is also a closed group here if you haven't already joined it called Men living with breast cancer which is a group is for men who are living with breast cancer, as well as their loved ones who are walking this path alongside them.
Does your dad have a GP who could help with getting answers from the surgeon or the oncologist? Or to provide information about seeking a second opinion?