Why Is My Child S Urine Red In Colour?

my daughter is 9 years, and sometimes her urine color change to the color red it could be pus or blood, and around her stool i find a red color also ... But she does not suffer from pain or diarrhea or constipation ... Usually i find on her underwear some Secretion ... We made analysis of urine and stool but the Dr. said she is suffering from inflammation in the urine and he gave her drug - Bactreim but the issue did not end and i am so scared and worried about her... She is not suffering from any other diseases, her food is good but before i made for her a blood test they said she has loss in iron... Thanks