what secret practices did the minister engage in as a result of the "immoral troubles" that beset him? why do you think he was doing this?

Dimmesdale also has become a masochist, and he uses chains and whips to beat himself in his closet. In addition he undertakes extremely long fasts, refusing to eat or drink as penance. This fasting causes him to have hallucinations in which he sees his parents, friends, and even Pearl and Hester. This sort of penance was quite common in those days and earlier. It became a physical manifestation, like Christ, of suffering and repentance.