My stomach hurts on and off lately, mostly after I eat?

So my stomach has been hurting a lot lately...usually after I eat. My mom thinks I might be lactose intolerant, I just drank a smoothie and my stomach is KILLING me. It's been like this for a like 4 days. My mom wants to take me to the doctor but I told her to give my two days. I hate the doctor. The pain is kinda in the middle of my stomach, right on my belly button. I'm twelve, if that helps..I guess. Any ideas??