Sporadic instances of depression and nostalgia

Recently I've been feeling strange. I think it has something to do with fall being here, and maybe I just feel more nostalgic around the later seasons, but it's like a constant thing! I like feeling nostalgic, but I experience nostalgia in a very strange, foreign way that I cant really put to words because it's always different. I get these sporadic bursts of nostalgia, and suddenly it feels like everything is standing still, and I'm longing for something, but I cant tell if its the past, or future, or both, or a future I want, or a future I want, but would rather keep wanting instead of having because my idea of it will always be better than the real thing. It's so intense, and I'm left totally incapacitated. I cant go to school, or work, or read, I just have to drift through this trying to figure out how to find myself again. That being said, I have recently experienced this, and it really disrupted my usual routine, and so I became depressed. 

I think of, and treat depression as an illness that will either go away with time or must be cured. I tried waiting it out, but it got worse, and so I toughened up, and took a really long shower which usually helps. I've been feeling better since, and I guess all I can do for now is learn how to handle this.