My daughter has white spots on her sidse an some on her tummy...They glow in the black light....An the doctors don't know what it is....?

Possibly Fungus. Tinea versicolor which is a fungal infection as well as others often can glow with black light. Your doctor or you might want to try an antifungal cream and see if that works. Or even better get a KOH scrape of the spots to see if this really is fungus.