Do doctors need consent forms to talk to each other?

Though most doctors will get consent from you to speak with other doctors on your behalf, they don't have to. Both parties have to keep confidentiality and cannot share it with another person, they are able to share information with other doctors on how to better treat you.

That being said, the family doctor must be treating you to do this. If you just knew of a doctor, but you were not under their treatment, they could not request your information.