9-year-old bent in two in pain. Ulcerative colitis?

Let me start by saying this has been going on for many years. For a long time I always thought she was catching a flu that didn’t last long, but that doesn’t seem to be the case. She gets these episodes sometimes a couple of times in a month, or sometimes she’ll go a couple of months without any. They seem to be completely random. These are her symptoms...

She’ll get stomach pains/cramps, sometimes accompanied by diarrhea and vomiting. She seems to be in excruciating pain, but no fever or any other sign of a flu. The pain will come in waves for an hour or two then subside completely. If she does throw up and have diarrhea, the pain goes away almost immediately and she’s back to normal almost right away.

This will occur typically in the middle of the night, not brought on my any specific food or anxiety. We’ve tracked everything she eats in the 24 hours prior to an episode, there’s never been any correlation between any specific food or type of food and these episodes. We’ve tried not eating for a few hours before bed, because she does like to have a light snack about an hour before bed, but it doesn’t seem to make a difference. She could do the exact same thing every day, eat the same thing but still have an episode randomly one night but be fine every other night.

She recently had blood work done and had a stool sample. The blood work came back negative, but I haven’t heard anything about the stool sample yet. She never has any visible blood in her stool. My mom does have ulcerative colitis so an issue of the bowel is of concern to me, but our doctor doesn’t seem overly convinced that it would be that since her main issue seems to be the vomiting and not necessarily diarrhea (she’ll have vomiting without diarrhea but if she does have diarrhea she’ll always have vomiting).

Has anyone ever seen or heard of something like this? I’m just at a loss as to what this could be and really want to help my daughter. Thanks for reading.