Im thinking this is a CAL - MAG deficiency ( first...

Looks like a calcium deficiency, not a magnesium. I wouldn't add Epsom salts. Adding Espom Salts to the soil may create more issues since magnesium and calcium ions compete for uptake into the plant. The more magnesium in the soil, the less chance that calcium will be absorbed. You can add dolomite lime, fish bones, seashells, and even crushed up eggshells can help provide additional calcium to the plants over time. Typically the ration you want is a 3.5-4:1 Calcium to magnesium in your water/feed schedule. It's too late to stop the damage you have, but calcium can help prevent anything further. I would add some organically. happy growing!!! 👊