I am a song writer, I have not been able to sleep on multiple occasions because new lyrics are always buzzing in my head. I do not hear them, I just think of different ways to put words together. It really is beginning to bother me, I will bump into people in public because I am preoccupied with words and how to rhyme, and fit them with music. I desperately need to know why I am doing this.
Vivian's answer is valuable. Do not overlook it. A poet and composer, I will also try to relate to your question. Again, I am not discarding Vivian's advice, but perhaps you will benefit even more from somebody who writes texts for music, among other literary activities.
Get the words (and music) in your head onto paper! Unless you really have no interest in lyrics or music at all and feel plagued by your perpetual thoughts about them, why not harness this creative power? As a lyricist and composer, I feel that any productive work is valuable. Moreover, noting down what you hear or think about will most likely ease any nuisance it causes.
This brings me to an important point: learn to leave your work behind. I do not mean to say that abandoning or destroying your creativity is in any way necessary. I mean to emphasize the importance in freeing oneself from any distraction. Once you have written down your thoughts (or recorded them onto an electronic device), they can be revisited when you feel you are ready to build upon them. Or, simply leave them. I am confident that you will begin to build a library of your own work and then, with time, learn larger lessons in regard to how your style has changed or improved. If you are in need of any further assistance, please email me: firstname.lastname@example.org. Thank you.
-Lars Christian Rosager-