tummy pain with vomiting! TMI!

My little girl is 5 years old. The last week (a little over a week now) she has been crying of tummy pains, it seems to only bother her at night time. The pains is around the belly button area, under right ribs, lower right side and lower middle abdomen. With these pains she experiences nausea, if I give her anything ANYTHING AT ALL, she vomits! 😖 Tonight she complained of tummy pain, so I gave her water. The water helped her tummy, but 20 minutes later she vomits EVERYWHERE!!! 🤢 The doctor doesn't know what it could be, they've even went as far to say she is lying about the pain. 🙄 I'm seriously overwhelmed. Any advice? 
Also I'm aware my grammar is terrible in the post, I'm working on cleaning this mess up and typing this in between my own nausea spells. 
Picture is just to show it's not just a tiny amount!