Sounds like you got yerself a case of the ‘Blossom End Rot’ m’Dear, which sounds more tragic than it is. Easily fixed.
Adding lime/calcium to your pots at the start was a good idea, but a top dressing again in the growing season would help. Container pots lose nutrients at an alarming rate because you’re constantly watering and washing away bits of soil and nutrients unless you fertilize (lightly!) each time you water...which can be 2x a day on hot summer days.
http://ohioline.osu.edu/hyg-fact/3000/3117.html
I have a hanging pot of “Tumbler Tom” tomatoes that need a nutritional kick in the pants, so to speak. I didn’t follow my own advice now, did I? Do as I say, not as I do, LOL!
Again, I’ll recommend a product called ‘Algoflash’ for tomatoes. Use that on your peppers; it’s a liquid fertilzer that is cranking out absolutely GORGEOUS toms & peppers for me this season...if they ONLY had a little more heat and sun. Grrrr!
http://www.algoflash.com/why_use_algoflash.html
Will get some lime on those babies as soon as the sun goes behind the trees and the plants cool down a bit. T/Y for the input.