What happened to this pygmy cory?

[OliveFish05]

Hi. I lost a Pygmy cory this morning. It looks a bit bloated and has a bloody red patch at the base of its abdomen. Tank mates are
5 neon tetras
2 honey gourami
a BN pleco
3 nerite snails

tank is a 20 long

water parameters are all in check, 0 amm, 0 nitrite, 0 nitrate. I used an API freshwater master test kit that was purchased two weeks ago.
I had a situation about 2 and a half weeks ago where I lost all the bb in my filter. I pulled a sponge filter from a different tank, but lost 5 neon tetras and a honey gourami in the first week. The parameters are all in check and none of the other fish are showing any signs of distress, disease, or stress. The two honey gourami fuss at eachother a little bit, one is definitely dominant, but I’ve never seen one go after a Pygmy cory.

The tank has a sand substrate, a large driftwood branch, a sponge filter, a heater set to 76, and is moderately planted.

 

[Oblio]

Very sorry for your loss, love my Corys (Albino Anaeus and Paleatus)
Maybe @Colin_T can provide a pathology report

 

[Oblio]

Now that I read your OP closer, how long is your tank? (20 (units?))
Any other Corys? (They should be in a shoal of 6+)

 

[OliveFish05]

Now that I read your OP closer, how long is your tank? (20 (units?))
Any other Corys? (They should be in a shoal of 6+)

A 20 long is 30x12x12 inches. Yes, there are 10 other Pygmy Cories

 

[StripySnailGirl04]

Perhaps he internally exploded when he/she had constipation???

 

[DoubleDutch]

Worms ?

 

[OliveFish05]

Worms ?

How can I tell if it’s worms? Is it possible its an injury of some sort?