Tarry stool

The black color stool resulted from your daughter's early nose bleeding that she might have swallowed some blood. If this is ture, you do not have to worry about any severe bleeding from GI system. However, I believe she had probably a primary viral infection in the beginning followed by a secondary bacterial infection. Several lab works need to be done: CBC+Diff; CMP; Sputum culture and sensitivity; Rapid strep throad test; Chest X-ray PA+Lateral. The doctor may start empirical antibiotics such as Amoxicillin or Zithromax while waiting for the culture result. If she has complication, such as dehydration or respiratory failure, she may be admitted into the hospital for IV antibiotics. Sorry about that.