Methylene blue?

I have an axolotl I've had for almost two months and about three quarters of that time he's had white spots thanks to fish I put in there that had it - at the time I didn't know he could get it from them.
He's had the white spot about three times now as I had to pull down his old bigger tank because of issues with it and I never treated the tank his in now, with not having known I had to do that too. He's been getting daily salt baths with 3 teaspoons of salt.

He has a white spot on his tail the size of a pinhead and while it seems to be very slowly shrinking, it doesn't seem to be going away, he also has something the same size on his toe but its turned black, so I'm wondering if he's growing another toe from the joint off the other.

I'm wondering if the white spot is becoming immune to the salt baths and if I need to try something else. I'm used to treating fish with Methylene blue, but I know you can't treat an axolotl like you do with fish. I've heard its safe for axolotls in small doses but how much is a safe dosage?

If someone can help me with this, it'd be great. Thank you.

To be honest I am not convinced this is white spot. I'd be very tempted to stop salt baths and various treatment and see what happens. Keep your axolotl in cool, clean water and monitor closely. I would think all the salt baths and so on must be really stressful for him.

Well I stopped it for a week after the first time and it came back. I also couldn't give him baths for two days in a row when he was just getting better and he got more spots. I was thinking the same thing.