I would just tell him/her that youve had some mood swings your concerned about and try to explain them to him/her to see what they say. There are several mood disorders out there and some of them act like BP. Like BPD, cyclothymia, etc. is similar in some ways so that could explain it to. I would just be up front about it mention the swings and see what they say it may take some time for them to sort it out but if your up front from the get go they should be able to help you either way.