My Butts Are Rotting

I think I might give up completely on growing tomatoes. I've battled blight, bugs, and now blossom end rot.  The tomato plants are beautiful and full of fruit, so you can imagine my disappointment at picking a handful of tomatoes and all of them have flat, black, rotten bottoms. Every. Single. One.

Google tells me this could be due to two reasons:

1. A calcium deficiency in my soil
2. Inconsistent watering and draught conditions

I'll go with door number two.  While I have watered them two-three times a week, it's been very hot and very dry.  I even bought a two-dollar sprinkler the other day to help.  I haven't made ketchup in two years and when the plants started putting on loads of tomatoes, I was so excited. Now that dream has dived into a pile of rotten butts.