I have seen feeders with most of their heads missing swim along without much care. it will be fine, goldfish are if nothing else tough survivors.
See... so you do have a quarantine tank. You just hadn't realized it yet. I've moved my betta around lots of times. For a few months, he had a whole 40 gallon plant growing tank to himself. Then I bought a small tank and got some fish with it I didn't actually want. They're not nearly as flexible, of course. So the betta is back in his 5 gallon, again. (He probably swears at me now.)So today Goldie is definitely doing better. He is almost acting normal he just looks like crap. lol. Has a very thick slime coating on the left side of his head where he scraped off all the scales. I also noticed that he banged up his tail pretty bad during the whole ordeal and it is looking frayed.
So last night I moved the betta into a bowl and let the tank sit for a few hours with some new chemicals and a 50% water change, then moved Goldie from the 50 gallon into the 20 gal. He seems to like the filter in this tank more, as the one in the 50 gallon creates a pretty strong current and that was just pushing him around as he tried to chill out. I went out and got some Melafix and added it to my tank just as you guys suggested. And am also feeding him some medicated fish food which fights against bacterial infections just as a precaution.
So I feel confident to say that I think he will be okay.
My pleco on the other hand is rather small only about 4 inches, and has never messed with my goldies before. I'm thinking I will leave him in the 50 gal as he will quickly outgrow the 20, and will just move him if there are any signs that he is causing trouble.