What's wrong with my Zebra Obiquidens?

[Cichlidbuddy]

Hello everyone, I've attached photos of my Obi that has a strange protrusion where either his anus or breeding tube is.
The bulge has fluctuated in size over the last ~8 months but he's never quite flat down there. There's been some breeding in the tank by other inhabitants so I thought at first maybe he was trying to mate, but it's big enough today to make me think it's a problem. Sometimes Obi has stringy poop, and he also used to have a bright red belly when I first got him, but the other fish scared it out of him a year ago. Not as pretty as he used to be, but he's fairly good at staying out of fights now. Other than the protrusion, seems healthy.

Since taking the photos this afternoon, I've put him in a QT, now just need to determine how to treat him. This website (Fish Fecal Disorders) seems to indicate that I need a product called Paracide-D. Has anybody tried this product? I have a cabinet of other treatments, including Prazipro, Kanaplex, Metroplex, a tiny box of impossible-to-find Furan-2, CopperPower Green, and aquarium salt. What does everyone think my next step should be?

55 gal tank -- Temp 82 F, PH 8.0, Ammonia 0, Nitrite 0, Nitrate under 20 ppm

Stock -- everyone is generally healthy with no injuries.
1 Zebra Obiquidens (m, "the patient" now in QT);
1 Red Zebra (f);
1 Blue Peacock (m);
1 Peacock (f);
1 Giraffe Hap (f)
2 Blue Dolphins (not sure, hopefully female);
2 Peacock-Kenyi hybrids (juveniles, m & f)
3 clown loaches

Thanks and happy holidays from NYC 🎅

[Colu]

That looks like an anal prolapse the best treatment is Epsom salt baths 1 table spoon for 2 gallons for no more than 15 minutes 2-3 times a day Epsom salt acts as a muscle relaxants help the fish to reabsorb the prolapse