What dosage of Epsom salt are you using? Keep him quarantined -- we don't know yet if he's dealing with something infectious or not.
I would start to increase the dosage up to 3 teaspoons Epsom salt. The procedure below is based on OFL's recommendation for doing this:
- Add 3 teaspoons Epsom salt to one gal of water. (The water should be the same temp as his tank temp.)
- Add the correct amount of conditioner.
- Stir/shake until the Epsom salt is completely dissolved.
- Using this premixed treatment water, make 25% water changes every 15 min for 1 hour today.
- Tomorrow, do a 50% water change using this premixed treatment water.
- Then, every other day for 10-14 days, do a 50% water change using this premixed treatment water.
Also, have you covered the top of the tank with plastic wrap? (Saran, Glad, etc. Any plastic wrap will do.) As mentioned previously, this will increase humidity levels in the tank, and help him breathe more easily.
Can you post a few more photos of him? It might be helpful to see a side view, and an overhead view. This would allow us to determine whether his whole body is swollen, in addition to his face.
If the 3 tsp Epsom salt/gal dosage doesn't work quickly, I would consider adding an antibiotic. It'll need to be something that acts both internally or externally. Kanaplex (Kanamycin) would be ideal. It's available at some high-end fish stores, or online.
(If you can't get Kanaplex, you can try tetracycline. For tetracycline: You'll need to add it to his water and also soak his food in it.)