5 year old with chronic abdominal pains

My daughter has suffered from abdominal pains for a couple of years now. Many a visit to our GP, bloods, stools all advising nothing wrong!
Clearly there is something wrong, the poor thing has terrible pains.
It is a central pain around her tummy button area.
She screams out, bends over and there seems to be nothing I can do for her. It doesn't seem to be food related as we have eliminated foods at times & she can still get the pain. A warm heat pack can help ease the pain, but not straight away, when the attack as I call it happens, she basically needs to just sit or lay down and crawl up in a ball until it dies a bit, then we can rub and apply heat.
I write this and feel terrible that it has been ongoing for years, without us really knowing whats going on. The GP did say it could be abdominal migraines....but this usually is grown out of, whereas I feel she is getting worse.
Has anyone dealt with anything similar?
Can anyone recommend a paediatrician in Auckland to see about this?

How frequent are they?
Is it usually after meal times?
Is she eating a lot of wheat or dairy?

Have they ruled out bowel obstruction, gall or kidney stones, cyst? Have they done a scan of area?

Next time she has an attack take her to hospital, they will have a better chance diagnosing her if they see her while this is going on.

If it is frequent reaction then you need to get a through medical done before moving on & treating the pain.