These things can be so difficult to watch--I've only had two personal experiences where fish have had very sudden changes to the appearance of their heads, and in both cases the fish died extremely quickly after presenting symptoms. It's definitely wise to keep dosing the JFE as per the instructions. Early termination of antibiotics can have serious consequences--to learn more about how antibiotics work and the risks involved, I suggest reading this article when you have time: http://edis.ifas.ufl.edu/fa084
I agree with OFL that this new infection is likely a secondary infection that was presented with a very grand opportunity once you stopped treatment with the antibiotic. Some bacteria become highly active around 80 degrees or so, so keeping the temperature lower, around 76 degrees, can be extremely helpful in some cases. If he continues to improve up to the end of the antibiotic treatment, it may be helpful to dose the water with methylene blue in order to discourage a secondary infection or parasite infestation during his recovery.
Epsom salt baths may help with the swelling on his face and the popeye, but if he is very ill, you might just want to add a smaller amount to the water he's in rather than do bath treatments. Make sure to examine the packaging for any warnings against using that medication with sulfates or sulfa drugs like Epsom salt, which is magnesium sulfate. I have no idea what caused the swelling in the face, and without palpating the lump (which no one but a veterinary professional should do) we don't know if it's some kind of abscess or blister or some kind of hard tissue growth--it's very hard to say what might have caused it.