It appears to me as if your plant has a magnesium deficiency. I would spread a couple of cups of Epsom salts around the base and out to the drip line and water it in well. Also, on the first picture I see what appears to be a sign of a fungal infection, the little circular spot with a halo around it. This could well be the beginning of a serious problem. I would spray either a copper fungicide or FRESH neem oil on both sides of all the leaves.