What’s wrong with my pepper?

What’s wrong with my pepper?

I've never had very good luck growing peppers, so I was excited when this year's pepper plant seemed ready to produce a healthy crop. Then, as the peppers started to mature, almost all of them began to show brown spots near the bottom that grew and became sunken over time. This photo shows both an advanced case and one that's in the earlier stages. As you can see the rest of the plant appears healthy: I've never encountered this problem before. Does anyone know what could be causing this? What can I do to resolve the problem? If it helps, I'm growing the plant in a container on my deck where it gets very full sun. I live in Philadelphia--zone 6. Thanks!
Canadian empty room!

Canadian empty room!

Esperanza

Esperanza

My tiny apartment!

My tiny apartment!

on elephant ears and rubber plants

on elephant ears and rubber plants

Pictures – just because

Pictures – just because

my new room

my new room