Help Sick Severum

[Seetrix]

Hey I just bought a green severum named ernie lol 3 days ago about 3cm big and when I fed it today I has what looks like a hemaroid haha sounds strange but it's got like a pinkish thing hangin out his butt with poo out the end of it. Any ideas of what it would be and if I should be worryed about it hurting him or my other fishies

 

[waterdrop]

post in emergencies and see if you can get Wilder's attention