What the hell is this? Is this a cal mag deficiency? HELP! It's spreading upwards

Guide to Nutrient Deficiency or Toxicity check out this link right here on this sight very helpful/useful.

its natural for a leave that close to the soil to discolor, if it continues to go let it a day or 2 before its totally ready to come off, then clip it surgically.. its natural the bottom leaves start to go!