Bactrim for kidneyreflux

My daughter is 5 yrs old and she was recently diagnosed with right duplex kidney with grade 2 and 3 reflux in this side 1.5 cm ureterocele and a hydroureter. She's been taking 6.5 ml of sulfamethoxazole-trimethoprim however she has been complaining of pain and her urine shows she may have a breakthrough uti so they upped her medicine to 13.5 ml every 12 hours for 10 days. Is this to much and can it cause issues with her liver or kidney?