I want to tell you why I believe people get sick...In 2 Chronicles 16, verse 10 - and I like to read this - verse 10 and 11 and 12, the bible says sickness comes when individuals attack preachers.
"Then Asa was wroth with the seer."
He's the king, and the seer was God's servant.
"and put him in a prison house; for he was in a rage with him because of this thing."
Because, see, he had prophesied something to him. And now this king named Asa oppressed some of the people the same time.
Now he had been, he persecuted the prophet of God and began to oppress the people.
"And, behold, the acts of Asa, first and last, lo, they are written in the book of the kings of Judah and Israel. And Asa in the thirty and ninth year of his reign was diseased in his feet, until his disease was exceeding great: yet in his disease he sought not to the LORD, but to the physicians."
The reason this man was struck with sickness is because he had been persecuting God's servant and oppressing the people of God. We see in the Word of God, God declares in His Word, "Touch not mine anointed and do my prophets no harm." Now that was spoken concerning Israel, yet applies to the body of Christ today, and we must be so careful not to attack men of God even when these men of God are not living right. (From Praise The Lord, Trinity Broadcasting Network, June 8, 1998.)
Perhaps that explains why Paul had a thorn in his flesh - for criticizing some of the wayward peddlers of the Gospel. It's worth noting that he takes "touch Not mine anointed" out of context, as it referred to physically attacking and killing Saul, not criticizing him.