Clearly I'm not taking a vacation from crazy

I'm on vacation this week and I spent a couple of days at my grandparents'. At one point when I was trying to fall asleep I experienced a strange feeling I've had before, best described as "dissociative homesickness." A brief but intense feeling of loneliness that comes out of nowhere, and happens when I'm away from home. Dissociative because I feel outside of myself when it happens--I'm always analyzing it as I'm experiencing it. I feel so profoundly alone, and as though there's someone I deeply miss. And then I run through all the people I might possibly miss, and it's none of them. But it's such a specific feeling, missing someone, and that's definitely what this feeling is. It's almost like deja vu, it has that sort of eeriness about it. I don't know if it's connected in any way to being bipolar or if it's unrelated; it happens rarely but I can remember it happening back into my childhood. It's just very strange, like an extremely condensed depressive episode or something. I mean it's over in a minute, but it leaves me struggling to figure out for a long time afterwards.