Any chance she has an external yeast infection? That can often cause the painful urination, but won't necessarily show on a urine dip. Sore vulva -> painful urination -> avoiding peeing -> peeing little amounts because it stings so bad -> peeing more because bladder isn't being emptied. Especially common if she's wiping herself (or not, as the case may be. When it happened to DD, I started paying attention, and she had decided she didn't want to wipe anymore, which caused her to chafe due to the wetness).
--Mimi
Mom to Lala (2004), Bonus Mom to Big Sis 1 (1991) and Big Sis 2 (1992)
Grammy to Big Kindy Kid (2011), Big Pre-K Kid (2012),
Grandbaby Appendage (2014), and New Baby Grandboy (summer 2017)