Blossom end rot (BER). There is a ton of discussion about this. Extremely common early in the season and with certain varieties (paste tomatoes are the most prone - San Marzano, roma, etc.). It's not a disease and it doesn't spread. Causes range anywhere from calcium deficiency to wild swings in temperatures to not enough sun to growing too quickly to.. you get the idea.

Wait it out. Not every tomato will get it.

It's Blossom End Rot, also known as BER. A common problem thought to be caused by the lack of mobile calcium in the plant. Most of the time it eventually clears up by itself over time. There are lots of threads on this problem and possible cures. Definitely remove any you find and toss 'em.

And check out the FAQ here on BER too for more details.

Dave

Thanks all for the diagnosis I was in panic mode foe a minute. I believe I can straightn this out.
Thanks again
Randal