I wrote a song a few years back, put 'my own tune' to it, and sang it from time to time. All during this 'creative' time, I had a sneaking suspicion that this was all too familiar.
Oddly enough, about three weeks ago (a year and a half since I last sang it), I got this uncontrollable urge to download and listen to a song that a woman I used to play music with, about ten years ago, used to sing: Mary Chapin Carpenter's "The more things change (the more they remain the same)". The words were mine, OK. It was 'bluesy' as opposed to 'country', but 99% of the tune was hers.
Oh dear!!

It is a common fear among 'composers', because there is not an infinite amount of permutations you can arrange the notes.
Also probably why 'The old ones are the best'

B.