Blossom end rot
Blossom end rot is not a calcium deficiency but rather a potassium excess. Manganese is the regulator of potassium. A foliar of chelated manganese along with fulvic acid will regulate potassium, either eliminating the deficiency in the plant or regulating down the excess.
With K or Ca excesses or functional deficiencies (i.e. when there are adequate amounts present in the soil) manage Mn and B. Mn regulates K and B regulates Ca.
Note that Mn triggers reproduction