What worries me is that the parasite is still present. It could also be velvet. A 2 day treatment is not long enough to kill the parasite. A good treatment with a med such as Cupramine you run for 14 days, that way you are sure to get them all. With the lifecycle lasting up to several weeks, there is now way you can kill them all in 2 days. They are only vulnerable in their free swimming state. Not all hatch out of the trophont state at the same time.
Now things are complicated with the possible secondary infection. He may need an antibiotic treatment, but you need to tackle the parasite first. Here is what I suggest.
Find some cupramine and the test kit that goes with it, seachems multitest kit. The test kit is a must. If you can't find one, I will UPS you mine (don't need it right now).
Run the cupramine, it is well tolerated by most fish and is very effective. Also he needs to see. I would put some epsom salts in the qt
to lessen the inflammation. 1 Tbs per 10 gallons, redose it every three days.
That along with keeping the water quality high, hopefully will clear him up. With high water quality, he should be able to fight the secondary infection off on his own. If that doesn't happen, you could treat with a broad spectrum antibiotic.
You need to tackle that parasite first.
Let me know, I have plenty of cupramine and I also have the test kit.