I'm losing my memory, and it's making me scared. Help?

I'd say the past 3 weeks my memory seems pretty bad. Like just now I couldn't remember when it started, I had to look on my calander and really strain myself. It's things like long term and whats recent. I graduated high school a few days ago and it feels like it never happened. Prom was last week and I barely feel anything. Like I remember some of it, but it feels like my brain isn't pressing the record button to record memories. What could be causing it? Hormone changes? Stress? Medicine? I'm on lamictal for seizures, but i've been on that for a while and never had problems. Will my memory come back once I figure out whats causing it? Please help, i'm getting really scared :(