Deficiency?? Can't find a plant like it...

Hey guys,

So I have a plant I have been growing and it just started having a lot of the fan leaves turning yellow, adn getting brown spots along the middle of the leaves. I have seen many pictures/articles about N and Mg deficiency, but the dont' seem to really look like my plant. It is in its 3rd week of flowering and getting worse. It is under 400W's and in miracle grow soil. The other leaves seem just fine, but maybe 1/3rd of my plant is now yellow, and almost all of them have many, many dark spots forming in the middle of them. Please advise.

Possibly a potassium deficiency?

Also the brown spots go away adn teh whole leaf turns yellow, but it doesnt do it from the outside in

The red in the stems says it is a deficiency and I already did my pondering in the reading room where I keep the book that has that info. It IS a deficiency, but I cannot remember which element. The red stems.....