Poor tomatoes

Our tomatoes have rot bottom. What a total bummer!
I don't know how it happened. Earlier in the process I read up a few articles and one suggested to prevent rot bottom, to add some egg shells in the bottom of the soil. So I did. But they still got rot bottom. We picked up something at the local home improvement store to boost the acidity in the soil but I don't think that helped.
I guess there are a few tomatoes that are OK. I just hope so! Some of the tomatoes are starting to ripen...going from green to orange to reddish.
I was so hoping to enjoy fresh veggies. Truth be told I have a horrible green thumb. The oregano or lettuce wasn't picked before flowering so I probably can't use them. And now the rot bottom on the tomatoes.
I'll give it a better try next year.