I have been finding it hard to write the way I used to, for those who know about rapping i can jot down 16 bars with ease, or finish a full song, but after dropping my single in January I can't come up with a good idea [emoji]. Anyone knows how to deal with the writer's block issue.
You're basically asking how to be creative, and maintain a creative streak.
You said you could jot down 16 bars with ease, but... how? You need to look a bit closer. What made that moment so easy? Analyse how your creativity works, and you'll find that your new work comes even more easily.