16 month old baby is in pain when his umbelical hernia is touched. he can't sleep lying down.

See a surgeon: Most umbilical hernia in infancy resolve spontanously. Meaning the baby outgrows the condition. But if it is causing pain then you must take your baby to see a pediatric general surgeon to evaluate if the condition is a surgical case and should be repaired. And if your baby has been fine until now and all of a sudden gets fussy when the hernia is touched, more urgent to get seen.