A healthy Discus should be able to go for a couple of months without food if they have to. You can nelp him along by removing incompatible tank mates, of which you have a couple
Most Danios
The Yo-Yo loach
Will stress the Discus usualy. Discus associate fast movement with danger, and the Danios are realy fast movers. This puts the Discus in a constant state of alert, and also stress. The loaches are nocturnal and again very active. They should not be mixed with Discus realy, for the same reason the Danios shouldn't

Also, Danios are cooler water fish, and Discus need it warm, arround 28-32 centigrade. This could prove an issue for your Corry's, depending on what species they are
To get the fish eating, remember to offer lots of feed regularly. You're looking at 5 feeds a day with at least twice a week 50% waterchanges for 4"-adult fish, dailiy waterchanges if they aren't that large yet

Don't just offer blood worms, as this realy is a poor diet for them. Mine get;
Vipakraft Discusin for the staple, twice a day
Tropical Quintette frozen mix, twice a day where possible
Left over veg like de-shelled peas as and when cooked for the family
Discus are still considered hard to keep, because people keep blundering into them without bothering to get off their backsides to do a little research. With the corrent care they are not difficult, but you only know what the correct care is if you have reseearched them. There a loads of different methods of keeping Discus, so you are talking about 6+ months on-line and in books looking at the methods and choosing which you think is best. If you don't do this before getting the fish, you often end up with dead Discus.
With all due respect, if you don't get into researching them soon, you are likely to fall into the group of people that consider them hard to keep because they were too ignorant to research their pets needs BEFORE purchase

Above all though, remember that these are an advanced species, but not always advanced enough to read.

Don't expect their behavior to be text-book, as their lack of reading ability means they don't know how they are supposed to be behaving, so they just do what comes naturally
I define someone as adiquately researched to have a good go at Discus, if they can pass a valid answer to most Discus questions on the forum, from basics to the advanced topics
All the best
Rabbut