You said you already tried epsom with no effect.
Since you already tried it and you even tried calmag, maybe you have a lockout.
Have you checked the ph of the runoff, it might give you some insight.
How long ago did you start treating? Mine might have only taken a week but I was using...
I'm still thinking mag issue, maybe someone else can suggest something.
I never foliar fed mine. 90% of my leaves recovered in a week but they were worse than yours by the time I started treating.
I used about 1/4 teaspoon of epsom to 3 gal of res. Too much epsom can also cause problems too...
My plant started exactly like that, and got worse cause I let it be for a week after noticing.
It was mag deficiency. To me, that looks like mag deficiency for sure. Calmag or epsom salt, mine cleared up with epsom.