o2zen, that first pic looks distressing. As I said I've never had any experience with carpets except my own but when my guy deflates his mouth isn't prolapsed like that.
I see the hollow you made for him, I'd fill it back in for him now since he seems willing to stay there. He may be too weak to dig in any further. A good sign that he will eat. Tell me about what you see the clown eating from his insides, is it brown stringy stuff? From what I've seen my guy do he should be expelling a neat slimy little white packet of bones if you are feeding silversides. Are you sure you have the Salt water Silversides? Now more than ever its important that he gets the most nutrition out of anything he eats. Actually if I was in your place I'd go to the grocery store or a fish market and try to buy him some squid tentacles or octopus tentacles because they should be pretty easy for him to digest without the bones etc.
The last pic looks better but he is still in some distress, when my guy deflates the next day he is WIDE open, his body is very thin and firm and he is at his biggest. He looks like a womans flared skirt on the dance floor.
I'm really sorry to hear about your heater and the Cucumber, don't cucumbers release a toxin when they expel their insides? If so you will need to take some immediate and drastic action. Is it dead? If not can you move it to your QT tank in case it dies? You will need to do a huge water change, I'd go 75% at least and run some carbon. If you can't do 75% all at once then 25%daily for 5 days.
Did you do any tests on your water since the heater and cucumber incident, I'd test ammonia and trates. How many hermits do you think died? If a lot of stuff died then you might have an ammonia spike or a small cycle again.