Firsttimerfreegelato

This really turned to shit in the last week. I had noticed soon after triggering flower a couple yellow leaves on the low part of the plant. Assumed at first it was lack of light. Then all of a sudden so many leaves have turned yellow and others are showing red veins. Assume it calcium deficiency and add cal mag for the first time. about a 1/4 tsp in a litter of water. So far no change.