re mood stabilisers, before I was diagnosed with BPD I was on some mood stabilisers but I had an allergic reaction to them. I forget the exact reason I was prescribed them anyway as I have always suffered from low mood only although your description of having normal moods then swinging to crushing depression describes me perfectly... When I was first diagnosed with BPD I was on several meds including mood stabilisers and anit-anxiety meds, as well as antidepressants. Since I was on them all at once I don't know which ones helped what (my head was so fuzzy and I was in such a bad space I couldn't figure anything out) but I guess that each and every one of them worked together to get me into a better space. At the time, though, I was battling psychosis so that have influenced the meds I was on too. I don't think this really helps your query, but it's just my own experience with them.