Rapid demeanor change

My axie, who's name is Hammy due to his extremely funny and outgoing demeanor, is suddenly very reclusive and stiff and is off his food. He's generally a pig and is begging for food even after he's eaten his rations.

A few days ago He started this decline and is really only seen moving when he's going up for air a few times an hour. His gills vary from bright red and pressed against his head - almost like he having trouble getting air - to relaxed and pale due to lack of movement. I tried to feed him and he's still not eating and not even showing interest in food. He's a golden albino color and is still a juvenile, probably about 6-8 months old or so. Maybe 8 inches long?

My husband informed me he put in some algaefix in his tank the other day to try and fix the brown algae problem without me knowing. He did dose it appropriately for the tank size, nut didn't realize axie's are more sensitive than fish and I'm wondering if he's been poisoned sue to this.

Is there anything I can do at this point - nearly 3 days later? Should I get water conditioned and fridge him or just wait it out? I'm really worried about my little guy and I'm crazy attached to him.

First, I would do a big water change. I also would tub him with fresh dechlorinated water for the next few days. After a few days, maybe do another smaller water change to be safe?

I agree with Krispy. You might want to change 100% of the tank water to remove the additive and tub your axie to monitor recovery. Test the tank every day or two to watch if the cycle crashes.