so where are they going yellow from? bottom up or top of plant or what, this is important because it will tell whats wrong, the bottom leaves going yellow is a nitrogen deffiency where as if the whole plant is going yellow it can possibly be a ph problem or a salt buildup thats locking out lots of nutes......which is what im guessing, i would stop the epsom salt spraying and flush with half strength solution ph'd to 6.5 or so for soil and them wait a few days to see if it works, dont expext to see the brown spots clear up as thats usually dead tissue and wont recover