Do a bunch of substrate vac's (like every few days), coupled with pwc as stirring up a lot of muck in the tank can elevate nitrates. Test water parameters. But if it isn't in a safe level, get it down to a safe level. Use Prime extra as needed between pwc.
The other things which can appear in the tank are Planaria and Hydras. Check out what they look like so you know.
Cut your feed to half of what you are doing now for a week or 2. (as a trial basis - continue if it seems appropriate, it is all to easy to be an over feeder - I am & trying to recover
) If you have begging fish who act like they are starving, then divide the half amount in 2 and feed earlier in the day and then later so they get to eat 2x, or so you can enjoy watching their feeding time too.
What size is your tank, maybe a new fish might be in order that you would enjoy and also likes to eat them.
After the tank clean up. Up the frequency of pwc - let's say if you only do one 1x per week then do one evey 4-5 days instead, and increase the amount like if you do 20% then try 30-35%.
These are all things to try. Test your water for a couple weeks every day or so and see if you can't get it freshened up in there. If it is detritus worm, the worm can go away on their own when the substrate isn't as mucky and enjoyable/nourishing for them. Or at least only be a small number you don't hardly see.