what medium are you using? I would adjust the ph to 6.2 to better absorb the potassium you do have left which is in my opinion the cause of the red stems. The spots are more troublesome, they were not there yesterday? Just start to cover bases, spray neem, raise ambient temp, lower humidity, check for parasites, foliar feeding (iron, sulphur, Calcium, magnesium)..epsom salts have the mag and the Sulphur and also stall viral and fungal growth when sprayed. Also if you have it, use a root zone conditioner(Zone by dutch masters is great.) Your roots might be rotten and an aggressive dose of zone or Hygrozyme will put the brakes on that. By the looks of it, you can save these. You flushed them into shock perhaps...add 1/2 strength nutrients or more maybe. If you use a silicate Pro-tekt, sil-pro break it out. B vitamins, If you dont have a root zone conditioner try beneficial bacteria and fungi. They do wonders to combat pathogens in the root system as well as optimize nutrient uptake and are like steroids for the roots. If you arent using them already....I strongly advise you check em out. I know it sounds like a ton of shit to do all at once but you dont have time for half-measures. The spots look fungal, my guess is it is water related. If using containers, you can take a skewer and poke into the soil to aerate and perhaps use a more powerful fungicide (Sulphur, potassium bicarbonate (green cure)) baking soda and water works pretty well, just dont use any of these if you have used any oil based sprays on the leaves in the last 4 weeks. They will bounce back.