sick golden puffer: help please

[saltyESQ]

After coming back from a weeks vacation and a friend taking care of my tank, my puffer is having breathing problems.

I first noticed that he wasn't getting up to greet me. Then the other day while feeding he just collapsed to the sand.

I tested for ammonia and it came back at 25.

Then 2 days later I did a 25% water change (50g) and added a bottle of amquel.
I then did a full range of testing
PH 8.0
ammonia 0
nitrite 10ppm
nitrate 10ppm

it has been almost a week as of today and my puffer still runs out of breath and needs to rest. when he lays on the sand he breathes really heavy for a few min then his breathing slows to normal. Also when he swims, his fins are not their usual stride, but very aggressive.

The tank is established 4 years and is 210g with 80 or so lbs of LR and 240lbs of LS.
bubble king super marine 200 skimmer and 114w UV
I also recently added a bag of carbon to the sump.

no fish have been added for almost a year. I have only added a sea hare and 2 snails in the last month.

tankmates:
humu trigger
flagfin angel
emperor angel
regal angel
singapore angel
golden puffer (meg)
blue spotted puffer
pearl scale butterfly
maroon clown
sohal tang
purple tang

I was thinking that the ammonia must have been a lot worse. Could the ammonia have burned his gills?
if so, when will it heal?
does anyone think he picked up a parasite?

what does everyone think?

any help is greatly appreciated!

[LilGreenPuffer]

Hey, it can be kinda confusing for folks when you double-post.

I answered you in the Hospital section.

[Troender]

Please do not double post. I'm closing this topic.