The Hatzolah part could be 1. that when he heard that a kid was complaining of chest pain he figured it was nothing. Which is likely the case in 99.99% of the time (unless there was some sort of trauma). But when he heard that they called Hatzolah he may have changed his mind.
2. He may have had similar occurrences and it turned out to be nothing each time. But when they called Hatzolah…
3. The story he was told the first time may have been different than what he heard on his radio.
4. He may have gone so others shouldnt have to come for nothing.
Edited