Vet costs???

I was wondering if anyone knows how much a check up is for an axolotl. possibly shots too, but no surgery for sure since there is no gravel or anything for him to ingest. bare bottom tank. This is what is going on...

~ Lived in a 15g tank from 4in to his now 7inches. No filter, no aeration, and was always happy, hungry, growing, and pooping. Did my water changes whenever he pooped.
~Decided to upgrade to a 20gallon long tank
~Was never told by the breeder about the cycling process, and assumed that since he was in his old tank, no cycle, plenty of complete cleanings of tank and everything in it with no problems, figured that he would be fine.
~Used his old water, old ornaments unwashed, and added fresh water and put him in.
~Added live plants, and then a canister filter with a spray bar pointed at the glass, hardly any water movement.
~Ammonia went up to .5 (never tested the old tank, was not told by breeder, was told on here several times that .5 is not lethal, and that it went down so all good), but after a few water changes, went down to .25
~After the filter was put in (it was rinsed out, could be a coincidence), his gills started to diminish, turn pale. was not as active as normal, lost appetite, stopped pooping
~Read on here to keep the levels norm as I did, but he got worse so I moved him back into his 15g tank (last night) with fresh dechlorinated water, and have been doing the water changes. ammonia at .25
~today he pooped alot, and ate 2 small pieces of worm this morning, and again tonight. do not see signs of vomit.
~NOW he is only using his left gills and leans to the left. He is standing on his back legs right now leaning. He is more active, but not sure if it is good, or because he is uncomfortable? Took all the advice on here, but looks like its all not working temp is fine too, always has been. Maybe its just gas, his skin and eyes look fine.

Maybe there was something in the tank or filter that didnt get rinsed out, or bought some bad worms that got him sick, either way, if no one else on here has any idea, I would like to know what cost I am in for :/

What is the make and model of the filter? Just curious if this could be the problem. Maybe you should consider replacing the filter with a smaller filter or just an airstone.

Do some more large-ish water changes to keep the ammonia as low as possible.

I don't know what a vet would cost. The bigger question is whether you can find one within driving distance that will see an axolotl and have reasonable expertise. I think you have to make some local phone calls to get the answer to either question.

i got a 501 canister filter, the smallest one. says up to 30gallons max, but made for smaller tanks. I have read a lot on here about people putting in a filter, or changing tanks and adding a filter and the axie suffered. Since he has been back in his old tank, no filter like how I used to have him, he seams to be steady, but too hard to tell. doing large water changes, keeping him cool. no signs of fungus, red dots on back of gills (looks like on where the filaments were) so hope that is his red gills he had before growing back. its just strange how so many people add a filter, and they get sick. going to try a feeding, see how he does. does not seem to be getting worse, but not better either. I live near rockford, IL and there is a herp vet there.

he seems to be doing better in his old tank, even perked up when he saw me! ( I know it was only for food lol) ate half a worm and has not tossed it up yet. moving around a lot more! Man I was scared! The breeder was very helpful!