Is that red streaking normal? Also the holes in his fins indicate either fin rot or ammonia burns.. It looks like there is white poo coming out from one of the photos or is that just a glitch in the photo?
If the infection is internal, it can be very very difficult to treat. Kanaplex is absorbed internally more readily than other antibiotics, but still not entirely effective the way feeding a medicine would be. However, he's obviously too stressed to eat right now, poor guy.
It's kind of a guessing game and we don't want to make him worse, but all that medication and the HUGE ammount of epsom salt is really hard on him if nothing else. I would never give that much epsom but that's another debate I don't want to get into others would.. I find it really stresses out my fish and it also drops ph a lot. I wouldn't surpass 1 TSP..Plus that and the IAL which also softens water may be leaving you with some REALLY acidic water which could also be stressing him out. If he hasn't eaten in 6 days there may not be anything to poop out.. I see his belly is a little bloated, but it may be infection and not food, or it could take more time to work. I would cut back to 1 TSP per gallon epsom (make sure it's pure 100% epsom with no other additives.. look at ingredients).. and make sure you're treating carefully with kanaplex by premixing 5 units and then adding only one to the bowl. If you don't want to cut back, I would at the very least find a way to test PH. Also make sure when you do a water change you acclimate him slowly, the salts and meds are predissolved, and the temp is identical.. ideally use 24-48hr aged water.