I think I figured it out. I think It's a bacterial infection. I ended up with a big bacterial bloom earlier this week because my stupid self added a bunch of dry rock to my system after I took out a bunch of my established rock (that was stupid). I should have added the dry rock way before I removed the established rock. The bacterial bloom is almost completely gone and I'm hoping the cucumbers recover. They are moving around sticking to rocks and sand and I think still eating as they have their feeding tentacles out and digging through the sand