Hey bro, sorry, I am late, just seen this thread. Such problems are often hard ones.
The salt... is it the epsom salt that you have been adding or table salt or both?
If it ingested much gravel, it could be noted in its swimming - fish usually can't stay in water column but drop quickly to the bottom, very unnatural and noted immediately. It also could be felt in its tummy by massaging fingers over it. This'd be very unusual but has been reported to happen before.
Bloodworms have been reported occasionally to be sold bad or rotten.
I assume you got it when it wasn't little and the prior history of the fish is unknown. Who knows what it had been fed before and if the care was adequate.
The beginning redness points to a bacterial infection, perhaps in the bloodstream, like hemorrhaging septicemia. It is is, it will spread all over body, fins. Often it is the last stage and not necessarily the primary cause.
The fact that it fed in the middle of this ordeal may point to the digestive issue, e.g., it had problems first, then got better, managed to pass / metabolize the feed, then ate more and got same or worse problems.
You can bury it if it dies.
duanes , you ever see anything live this?
thebiggerthebetter
