Hi GoldfishGoddess,
I share your problems too,there is no supply of medicated fish food from the pet shops in Australia. This is due to strict registration requirements in Australia. So we have have to stick with our vet. This is driving me broke

However I've have been experimenting with Antibiotics like Metroglflagyl (hope correctly spelled)and Amoxycillin which I got prescribed from my GP when I got the Flu.

My Doc said it should be ok to my fish but he is not sure about dosage.(that's why I'm experimenting)here is how I make it:
I take about 1/2 teaspoon of Hikari Lionhead pellets and place them in a small bowl and grind it to bits with a soup spoon, then I add a small amount of Antibiotic powder to it follow by a few drops of water to soften it, and mix it again. Let it stand for about 10 mins. It should look moist but not too soggy, then finally, I add some cod liver oil (capsule type) and bind the mixture together so when it hits the water, it won't break up. It is now ready for feeding, I feed my sick fish twice a day and the remainder I keep in the fridge for the next day only, any leftover will be discarded. My sick fish always take it readily and I'm pleased with the results.
Cheers mate