Jesus didn't have to fast and pray to fnd out God's will to heal people.

He healed all that came to him.

He came to destroy the works of the devil, sickness is of the devil because it kills, steals [our money and health] and destroys [lives].

"The thief [the devil] cometh not but for to steal, kill and destroy, but I [Jesus] have come to give you life and give it more abundantly."
John 10:10