Why Did I Have This Dream?

This dream is scaring me! I had a dream that I was at a party and I forgot my cell phone at home. Mom pulled up and apparently was trying to call me on it multiple times. I came out the door and she was mad and yelling at me. Then, I killed her..with a pot. It was weird but scary! and vivid! I just kept beating her with it and then i stabbed the handle into her head. I love my mom, why did I dream this? I woke up crying like crazy. I'm on codeine and zithromax for my bronchitis, could that have been causing it?