Dear Patient, if a patient with your symptoms comes to my office i think about the following: This can be a kindney or urinary tract infection, or kidney stones. It is advisable to see a dr closely to rue that out by urin test and ultrasound. With the ultrasound also other organs in the abdomen can be checked (gall bladder especially, although gallstones very unlikely in young age) If it is not that: ultrasound of the reproductive organs through a gyn-dr would be the next step to rule out inflammations there. Eventually this can be the beginning of her first period also, but first i d rule out infections as advises above. Hope this is helping you , if you have any clarificatons you can get back to me, if this was helpful please kindly rate my answer. Best regards