Ashley Rose

This poor sick cory hasn't been doing so well for a while now. He has lost weight (I never see him eat) and looks and acts awful. So it started when I saw that his barbels were gone. I did a 75% water change when I noticed. I keep doing 50% weekly, treated with melafix for over a week.... only got worse Now it has so many red spots and ripped fins. I can't tell if it's a bacterial infection or internal bleeding or even a parasite. I want to mention it's behavior is so odd as well. It won't go to the bottom of the tank to join the other corries, it only swims around the middle of the tank (like actually swimming non-stop which is very odd for a cory?) If it's not swimming it's sitting on the plants.....it acts very lifeless No ammonia but my nitrates are like 30ppm Tank Mates are platies, mollies, cories, snails, shrimp, and a bn pleco Substrate is sand mixed with stratum 36 bow front with an aqua clear 70 and a sponge filter I feed every other day Any advice? It breaks my heart seeing it struggle :((