Final answer:
The nurse should report findings indicative of neonatal abstinence syndrome, such as the newborn's inconsolable high-pitched cry, poor breastfeeding, increased muscle tone, hyperactive Moro reflex, and several loose stools.
Step-by-step explanation:
The nurse should report several findings to the provider that may indicate the newborn is experiencing withdrawal symptoms due to the maternal history of methadone use during pregnancy. These findings include the newborn's inconsolable high-pitched cry, poor breastfeeding, increased muscle tone with moderate to severe tremors when disturbed, hyperactive Moro reflex, and the presence of several loose stools. These symptoms align with neonatal abstinence syndrome (NAS), a condition in newborns exposed to opiates in utero.