ReLaX:
Been there, done that, living it. I'm currently on Zoloft but since you're a starving college student, that may be out.
I'd find someone to talk to. That helped me through every situation you mentioned. The other thing is to get up and do something: go for a walk, do laundry, anything, just do something! A lot of my depession involved having too much time to sit there and "think" about my situation. If I started to do something physical, the feelings went away.
I've talked about suicide, a lot. I've even planned mine out, however, I currently have too many responsibilities to my family and friends to ever do it. PLEASE DON'T DO IT. Things can and will get better. When I was feeling suicidal, I listened to a lot of heavy metal music, very loudly. The heavy drum and bass beats helped me get out of my depressed mood.
BTW, mine started out the same way. Nagging little doubts, self-esteem issues, general blah feeling. It IS serious enough to get help. Trust me. It took my wife 15 years or so to finally convince me to get help. I kept telling myself, "It's temporary, it'll blow over" Well, over time, my moods lasted longer and longer. Finally, on the way home from work 3 years ago, I had to keep myself from driving off the road. Hmm, there's something wrong there (duh) Went to my doctor and he prescribed the Zoloft. No shrinks involved.
I wish you luck!