I have some acros/Millie that started looking bad. I dipped one and these worms came off they don't look like planaria though I do believe I have some in my tank.
What is the best course of action?
Looks like AEFW. Best course of action is remove all sps from your tank 8 weeks + especially if you only have frags.
If you are starting new with SPS and already are battling this, it will be a uphill battle of maintenance, and from my experience and research, unbeatable for 95% of aquarists.
I see you are from Fontana, try local seller SPS Tank for your coral after fallow period. He quarantines all coral that he sells.
I have heard that Potassium Chloride dip works well on AEFW and I have also seen ReefDudes on YouTube talk about lowering the water level in his tank and making a solution of Potassium chloride in a spray bottle to target Acro's that could not be removed and dipped.. it sounded like he beat it that way