Hi Cindy! Have you had a soil test to see if you need calcium added to your soil? Yes, a lack of calcium causes the end rot but why didn't enough calcium get to the fruit - that is the question. More often than not it is due inconsistent watering even going back to when the tomatoes were planted. The roots could have some damage that does not allow the calcium to enter the plant. The roots could be damaged from too much or too little water, from pulling weeds too close to the plants, or even from needing other nutrients.

So what to do: I recommend a soil test before adding any type of fertilizer or calcium (Home | Pickaway (osu.edu) ). I've included the link for the Pickaway County Extension Office so you can get a soil test there.

Make sure you water consistently during the rest of the growing season - meaning water the same time of day, every day.

Your remaining green tomatoes will be fine (I hope!). Often, blossom end rot hurts the first fruits more than the tomatoes that come out later. If you start to notice a spot on the bottom of any of them, pull them & let them ripen by a bright window.

Enjoy your garden!