Does appear to be a calcium deficiency called blossom end rot. But BER can be caused by a lot of factors: not enough water when fruit is forming, too much nitrogen, the wrong kind of nitrogen, it's too hot and dry, excessive levels of soluble potassium and magnesium can compete with calcium, etc. You don't state the zone where you live so it's hard to completely pinpoint what could be happening to cause this. In Florida we do not recommend foliar sprays as calcium on the leaves cannot be taken up by the fruit. Check your soil pH to make sure calcium is available.