First Post, need advice

Hi, I need some advice. I'm 23 y/o male. currently on the "trip of a life time" Australian travelling through Canada for 12 months. But I find it hard to be even interested in most of the things we do, my travelling companions always seem to be excited about every little thing that happens and every place we go and I usually lose interest.
I also had an extreamly short relationship with a girl here (less than a week) and it's all I think about and living in a small town I can't seem to get away from it. I've also noticed I have monumental mood swings and notice myself being very short with people.
I know reading back that it doesnt sound like much, compared to reading what other people have written. I find it hard to describe how I feel, all I know is that my moods and feelings are starting to effect every aspect of my life.

Am I depressed? should I seek out help?

It might just be a phase you're going through.
If the problem persists, I would definately see a doctor about it.