"Speak while I still can, or lose my tongue"
That popped in to my head as a rhyme for young sorry, felt like throwing it out there. Might not fit at all.
We've all been there with writers block. When I have it bad I have sheets and sheets of paper with short phrases written on them, all of them being potentials for songs. It really gets to me when I have a great line and can't flesh it out into an equally great song. I can really sympathise with you here.