Bipolar II disorder is not actually the "mild version", but is considered to be more of a life-destroying illness over time than type I (at least without treatment, although type II does apparently respond well to treatment). Maybe you have a mild case of type II, of course.
I think that you have to consider the possibility, if Bear's mood changes are severe, that he has a worse problem than you. Also consider that he might improve with just a mood stabilizer, and that if he takes an antidepressant that there are other options than SSRIs.
No matter what, I would get at least two opinions, possibly more, and ask for every possible battery to be administered to aid in a correct diagnosis.
