So little update: i did the metro food, and the holes have shrunk. one has left entirely. I think I've finally figured it out between your info, info from someone on another forum, and research. The metro food is helping the HITH, and he still has these tiny clearish pimples. That could be bacterial infection, probably caused by the HITH. I'm mostly still posting for your records if anyone ever has HITH problems and does a search.
I may give him soaked epsom as a precaution to see if he has anything to get rid of in terms of parasites so to speak. Right now he's getting Thera+A, NLS community, Hikari Carnivore with vitachem, Hikari carnivore soaked in metro (3x pellets), and Soilent Green (Repashy Gel food) for the veggies. All that is supplemented with mysis shrimp, SFBay's Medley, and an occasional omega one pellet/flake and zucchini/peas/fresh shrimp.
If anyone ever has a Syno with HITH, try algae since I read some info on PlanetCatfish that they need algae and lack of algae can cause HITH. Someone linked to a study done with another type of catfish, but I do not have it on hand. If anyone wants it I can link you to it. That is why I got the Soilent Green. Stuff stinks to high heaven but if it helps, it helps, smelly or not.