Cramping at 30 weeks

I'm 30 weeks pregnant (with my third baby) and for the past 2 hours I've been cramping pretty bad. I still feel baby moving and I laid down to drink some water for an hour but it didn't stop the cramps. This morning I was "nesting" and moving a lot of things around in my daughters room...nothing too heavy, just some boxes of clothes/toys. Should I go in? I will probably end up calling my Dr here shortly if they don't stop, but wanted to see what other ladies would do in this situation..I never cramped with my other two kids.