Illness/Sickness: Help?

My axolotl's gills have suddenly decreased in size. His longest ones on each side are about half their original length. I'm assuming they've been bitten off, as some of the fronds are missing in other places, but the affected areas look rounded off, as if theyve healed or shrunk.
Later on, he started twitching, as if snapping for food that isnt there, and keeps doing it.
There's no gravel in the tank that he could have swallowed and he hasnt been fed for at least 24 hours. Nothing other than his gills look out of the ordinary.
Does anyone know why he's twitching? I'm worried
Could the sudden gill deterioration be metamorphosis related?
Here's some pictures of the gills, if it helps. Also, he may be a girl...

I would say its likely your axie has a parasite problem, in particular, one caused by protozoa such as Oodinium pillularis (velvet disease), Charchesium or Vorticella. Protozoa infections can cause extreme irritation to the gills and skin and can cause the axie to 'snap' or twitch. In addition, gill fimbriae can be lost as a result and a white grey fuzzy (not cottony) coating seems to appear around gill region. Oxygen exchange can be compromised.

Fortunately, the treatment for them is quite simple and minially invasive. They all respond quite well to salt baths. However unlikes fungal infections, you would need to perform more salt baths per day for a longer period of time to be effective. I would recommend 3x salt baths/ day for 3 days and then taper down to 2x salt baths/day for 2 days and 1x salt bath/day for 2 days. Each salt bath session should be 10 minutes. There is no necessity to soak longer than that. By the end of the week, the condition should improve substantially.

You can also fridge the axie thoroughout the week during treatment.

thank you so much Rayson. I knew you could help me! I was so worried, I will begin salt baths immediately

Oh, also, is it contagious? I have three other axies in the same tank. I am moving the infected one to the fridge though.

Yes contagious, so best to isolate until fully treated. Different axies have different resistance to the parasites though, so one may be severely affected but others may be strong enough to fight off these infections.

How will I know when it is safe to return the axie to the tank? There seems to be some improvement, twitches are a lot less frequent. However I find white things floating around in the water, do salt baths or the parasite result in some shedding of skin? Skin is the only thing I can guess the white stuff is, looks thin and see through, small bits of it floating around.

Yes both shedding skin and parasitic elements can resemble floating bits of transparent white flecks. That is expected and normal. Persist with the treatment and i anticipate an uneventful recovery.