CC Adi 17.49, purport:

The deliverance of the fallen does not consist of curing their bodily diseases, although it is also a fact that when a man is delivered from the material clutches his material bodily diseases are automatically cured. Gopala Capala simply wanted to be delivered from the bodily sufferings of leprosy, but Sri Caitanya, although accepting his sincere appeal, wanted to inform him of the real cause of suffering.

CC Adi 17.50, translation:

Hearing this, Caitanya Mahaprabhu appeared greatly angry, and in that angry mood He spoke some words chastising him.

CC Adi 17.51:

“O sinful person, envious of pure devotees, I shall not deliver you! Rather, I shall have you bitten by these germs for many millions of years.

Purport: We should note herein that all our sufferings in this material world, especially from disease, are due to our past sinful activities. And of all sinful activities, actions directed against a pure devotee out of sheer envy are considered extremely severe. Sri Caitanya Mahaprabhu wanted Gopala Capala to understand the cause of his suffering. Any person who disturbs a pure devotee engaged in broadcasting the holy name of the Lord is certainly punished like Gopala Capala. This is the instruction of Sri Caitanya Mahaprabhu. As we shall see, one who offends a pure devotee can never satisfy Caitanya Mahaprabhu unless and until he sincerely regrets his offense and thus rectifies it.

Srila Prabhupada, CC Adi 17.49-51