Cramping on one side

I'm 12 w 3 d and have had pretty bad cramping on my left side all day. It's almost like the cramps I get when I ovulate. Sometimes it's I both sides. It's better when I lay down. I am carrying twins so I'm not sure if it's because of that or what but I'm a little worried. Is Anyone else have these? If it's still happening tomorrow I will call my doc, but just wanted to see if anyone else experienced this.