I treated the velvet using ESHA Exit, which after a fair bit of research did seem the best way to go as it's a fairly safe med for sensitive fish.
However since day two my Jaguar Catfish have been refusing to eat

I have noticed that they look pretty much as they were with the exception of very sunken stomachs. One of them actually looks like he's got a very "lumpy" stomach (almost like he has a belly of gravel in there). Also, they are now active until lights on (around 11am) they have always hidden away at dawn so this again is very unusual for them. Equally where previously they have always swamped my hands on feeding to get at the food now they swim a mile.
Have attached a short video of one of them taken minutes ago. I am at my wits end with all of this, these guys have been doing so great these last few months, yet now I feel so helpless.
Day after the final Exit treatment (2 days ago) I added the 3 x 100g bags of new carbon to the tank filter and did a 50% water change. None of this seems to have helped. What can I do? Are they likely to eat eventually (should I just persevere)? Or do I accept the fact these guys could simply starve to death?
Tank temperature is around 27C would reducing it back down to the 25-26C help?
I have toyed with the idea of moving them into the 30G tank on there own and maybe treat with a broad spectrum antibiotic? not sure about this given I have no idea what's going on.
Many thanks, and feel so guilty for all the advice I have sought from you guys these past few weeks. As above things atm just seem to be going from bad to worse. Thanks again