Koi Fish injured

Question
hey I'm hoping you can help me out with a question. I have a Koi pond with
koi and some goldfish in it. The pond is about 4.5 feet deep in the middle
and about 6000 gallons. One of my koi has what appears to be a "cut" or an
ulcer of some kind on the one side of his head. He swims fine and is eating,
I'm just wondering how I can solve this problem. We did put "Melafix" in the
pond which heals ulcers and diseases in fish, but so far I haven't seen any
improvement. This fish is our oldest fish and we're trying not to lose it!!! Any
help would be greatly appreciated! Thanks.

Answer
if you are seeing an improvement with the treatment you are using, stick to it for about 2 weeks longer, but if it grows larger you may want to look into a vet, i know it sounds silly, but the same thing happened to us, and we contacted a vet that willingy operated to cut it off, and 9 years later he's still goin strong, so it might be worth emailing around.