Vitamins?

Alright ladies so I'm in the market for vitamins. Not necessarily a multi vitamin but individual supplements to "fill in the gaps" where my diet might not cut it everyday. I've been noticing increased fatigue lately (for about 3-4 weeks straight now), inability to focus well, and I'm now at the point where I've started to lose weight (only about 4 pounds but I'm a very petite girl to begin with so it's difficult for me to put weight back on once I start losing it).

If you take daily vitamins/supplements what do you use? I need ideas!