Hi Anna -
Welcome to the Healing Well forum. There are a bunch of wonderful, caring people here. I'm not on this site that often anymore, since I've been focusing on dealing with my anxiety, but I read your post and it really spoke to me. I spent 3 amazing weeks in Ecuador in 2004 - it really was a wonderful experience that I wouldn't trade for anything! But, when I came home - reality set in. I needed to finish my thesis (the trip was my last class for grad school). I needed to find a place to live and a full-time job (that paid reasonably well, so I could pay my student loans along with all my other bills) and I needed medical benefits. Well, all those things kinda added up and sent me on a dark spiral downward. (I had trouble sleeping, I didn't want to eat, and I didn't enjoy doing anything anymore.)
But, one thing I realized as I looked for housing and looked for jobs and tried to focus on writing my paper was that the medication I took for Malaria really had a negative effect on me. So much so that one of my friends suggested that I see a therapist. But, as soon as my prescription was done (it was one of those meds that you had to take for so many weeks before you traveled to a malaria infested country and so many weeks afterwards) the dark cloud began to lift. I found a woman who agreed to let me live in her cabin in exchange for chopping forewood. Soon after that I found a job in my field in the area and about a year later, I finally finished writing my paper. But the thing was - I should never have taken that medication, since there was a waring that clearly said "Do not take if you have depression." But, I was still in denial that I even had depression.
So, perhaps what you are experiencing is also due to several different things all acting together. I mean starting college can make anyone stressed and coming down from an enormous high like the "trip of a lifetime" can also make anyone depressed. It sounds like you are on the right track, since you are already looking for solutions. It just may take some time. I do hope you get a good night's sleep and your appetite returns. But please know that the odds of having another great trip are really really great. (I went to Alaska this past summer and it was incredible! I'm not sure if it beat the trip to the Galapagos Islands, but it sure gave it a ride for its money!) :)