Poor axolotl's third and worst air bubble

Hello!
Recently I've adopted two baby axies from my teacher, one albino and one wild type. They were both doing well until the white one got his first air bubble. Over the past two weeks he's had a total of three air bubbles, each getting worse. Now they're very small, they're only about an inch and a half long. I feed them two to three frozen bloodworms a day, severed to a lout half a centimetre long segments. I do a 30% water change in a 30gallon tank every week, with treated well water.
My poor axie is floating at the top of his tank and can only swim to the bottom with great difficulty! He still has a ferocious appetite, but I don't think the air bubble is passing with regular feeding as is suggested on this site.
I fear he is too small to be fridged, but I'm not sure what else to do. He doesn't seem too unhappy to rest at the top of the tank, but in wondering if being in the big tank is stressing him? I don't want to move him to a smaller container for fear this might stress him too; the poor guy seems very ill.
I know there are several threads dealing with this, but I haven't found one for axies as small as mine. Any advice from anyone who knows more would be greatly appreciated.
(I've got two inch-and-a-half long axies in a 30g tank. Water stays around 19 degrees Celsius, or 68 degrees Fahrenheit. They have a filter with minimal flow, and a fine sand substrate at the bottom. I hand feed them two bloodworms each daily. Current air bubble has been there for about two and a half days now.
You can see in the photo they look a little broken up in what I guess are his intestines? He just ate a good amount and as I wrote this I think it started to pass. Still worried though

Update: he's still floating, seems to have bubbles on both sides of his abdomen, hoping the bubble didnt somehow escape from his stomach and get trapped somewhere else? If that's even possible.
I've moved him to a small Tupperware with the Indian fern so he can prop himself under it. Still hesitant to fridge him. Ate half a bloodworm this morning, going to the store to find earth worms to chop up and give him.