What could cause my 4 yr old to have a greenish brown vaginal discharge?she has a history of uti's.is this associated with that?

Possibly, but see MD: Urinary tract infections in 4 year olds rarely produce the discharge that you are describing. Some of the more likely causes are a "foreign body" stuffed into the "hidden cave", improper vulvar hygiene, soap allergies, the use of longterm diaper like underwear, and suspected sexual manipulation. See a pediatrician or a pediatric gyn md.

?somrthing in vagina: Vaginal discharge in 4-y-o might be due to foreign object in vagina. Little kids often insert small objects like beads, dried beans etc into various openings in body like vagina, nose, ears etc. Pediatric urologist, gyn. Or surgeon should probably take a look. Might require anesthesia for diagnosis + possible extraction. Good luck.