Sick juvenile axolotl bloated with bruised belly floating upside down

I have a 55 gal planted tank with 4 juvenile axolotls all around 7 months old. They all seemed happy and healthy and I fed them bloodworms and guppies, until giving them their first live black worms a few weeks back. They gobbled them voraciously, but the next day one of the females appeared bloated and she was swimming upside down. I fridged her and have done daily water changes, though she has not defecated to my sight. A few days in, she did expel a small snail apparently, as I noticed it during a water change, but she has no appetite and does not appear to be getting better. After 10 days fridging, her bloating has reduced but she still swims upside down and now has a red bruise on her belly that has gotten darker in recent days, and it feels hard to the touch compared to the rest of her body. I'm worried if she has an impaction and how I can help her through this. The other axolotls all seem to be happy and healthy, so I do not believe it's a water/tank issue. My substrate is 2-3 inches of sand on top of eco-complete soil, meaning she can't get to pebbles or choking hazards other than the small snails I've battled getting rid of. I'll attach pictures in hopes someone might recognize the symptoms and help me help this sick baby. Much appreciation.

The first pic was 3 days ago, the other is today. You can see the spot has gotten darker red in recent days. The other 3 axolotls still appear healthy.

is it still alive?

ryan_free said:

is it still alive?

Click to expand...

This was posted back in 2016. It's either dead now or it somehow made a recovery and is alive to this day but would be close to 8 years of age.
OP never responded to any help though so I presume the animal perished from this disease and the help didn't come in time.