AC1984

All right guys if it isn't one thing its freaking another. About two weeks ago I noticed that my tranny was slipping when shifting into 4th gear. ( Before this started everthing was fine) Now it doesn't want to shift into 4th gear at all. My O/D light works but it isn't flashing and my O/D switch doesn't work anymore and I think its because of the shifting problem. Someone please help.