How long have you had the aros in this tank? Is it a new tank setup? I've had aros with this before and treated with melafix in a smaller tank. However if you don't find the root cause it's likely to return. I found that it was a combination of using active carbon in my filter and general stress of the fish (I had just had them shipped in a couple weeks prior).
They can also get other fungal infections from open wounds, like if they break their barbells. Recommend you move them to a smaller medical tank temporarily, treat with melafix and increase temperature to 90 degrees Farenheit until healed.