Isaiah said, “Bring a cake of figs. And let them take and lay it on the boil, that he may recover.”
2 Kings 20:7

Why figs? It looks like medical intervention and Isaiah even attributes the healing to the figs. Isaiah's prophecies were sometimes of a very practical nature, and God often responds to our foolishness by ensuring that we suffer the natural consequences without divine rescue.

Figs are symbolic of fruitfulness, which Hezekiah had not been. He did not have an heir yet, which threatened the entire lineage of David because the previous generation had been wiped out by wicked people.

The flowers are on the inside of the fruit. Tiny fig wasps enter the fruit to lay eggs and often die inside the fruit. Their bodies are dissolved by enzymes in the fruit, but this is a picture of how fruitfulness often requires conflict, uncleanness, and interaction with things that appear to be forbidden.