Why did Huck "get to feeling so mean and miserable"?

Huck's Southern conscience is bothering him. He feel bad that he helped Ms. Watson's slave run away. He went against the racist norms of the South. This is why is feeling so upset. It comes in conflict with his own social code of liking Jim and wanting Jim to be free.

Jus a note...... you've listed this question under the wrong novel category.

He was feeling guilty about helping Jim escape because Miss Watson had always been so good to him.

"Conscience says to me, “What had poor Miss Watson done to you that you could see her nigger go off right under your eyes and never say one single word? What did that poor old woman do to you that you could treat her so mean? Why, she tried to learn you your book, she tried to learn you your manners, she tried to be good to you every way she knowed how. THAT’S what she done.”

I got to feeling so mean and so miserable I most wished I was dead. I fidgeted up and down the raft, abusing myself to myself, and Jim was fidgeting up and down past me. We neither of us could keep still. Every time he danced around and says, “Dah’s Cairo!” it went through me like a shot, and I thought if it WAS Cairo I reckoned I would die of miserableness."