Have you got a before picture of Finn? Does he normally have a darker head coloring like that? Is his anal fin bicolor with streaks of red?
As Sakura pointed out, there could be many issues with these type of symptoms. I believe his problem is beyond the SBD/bloating alone. I mentioned to you in my first post that he was a tail biter. They can do it really fast, they can do it at night while you sleep, unless you watch them like a hawk, most time you will only see the result and not the action.
I know it can be stressful, but If I were you, this is what I would do:
1) take Finn out into a temp cup
2) remove all the stuff from the tank, wash tank real well with hot water. Let cool.
3) in a separate jug/container, pre mix the 1 tsp ES in 1 gal of conditioned water = treatment (tx) water
4) pour tx water in the cleaned tank enough to cover Finn to breath easier
5) change water daily and repeat for 5 days and observe, may need to up ES dosage?
6) if you have the meds as Sakura suggested, add that to your tx water as well.
7) if you have frozen bloodworm, feed him to see if interested
Good luck with Finn!