Blue tongue health concerns

[Auguriim]

One of my eastern blueys, Bajo has been sick for a while, took him to the vet and they said he was healthy and prescribed ivermectin in case he had parasites, then took him back again after he started to display heavy coughs and sneezing and I’m given some antibiotics (baytril) to give to him orally everyday for 10 days. Tomorrow is his last day of antibiotic treatment. I definitely seen some improvement midway, he was active and isn’t sneezing/coughing anymore. Now he’s kind of going backwards in recovery but I heard when they look worse it means they’re getting better and clearing all the crap out so maybe that’s the case?
One thing that’s not going away is his eye issue. He always has either one or both closed but during days when he has bursts of activity and whenever I take him out he was completely fine, eyes are wide open. Sometimes he tries to rub his eyes against a rock. He is on paper towels now but his substrate before was a mix of euci mulch and coir potting soil, I know he gets irritated eyes from coir but it’s often when it’s was the base substrate and he had no issues when it was mixed. His eyes aren’t swollen, red or bubbly. They appear completely fine.
I tried looking it up but haven’t really found anything similar to his case so I don’t know how to fix it. I tried wiping his eyes with a damp paper towel and gave him a soak and still nothing. Anyone here have a similar experience?