Meds poor in Australia as well. Now I either hospital tank or put down straight off. You can try any anti-bacterial treatments available.
Just gone through a dozen tiger barbs here. My success rate at healing is very low really.
Sometimes an anti-bacterial to ‘clean it up’ followed by double course of antibiotics. Here that might be malachite green followed by triple-sulpha. If it is just fungal the anti-bacterial will usually deal with it quickly. Some people report success with salt.
And as above, good water conditions.
I find a stable tank better than trying to lift tank temperature to kill it off but opinions do vary locally on that.