Most of my tomato plants got off to a great start this year, blossoming early and abundantly. However, very, very few are pollinating and in the last week, blossoms have begun disappearing. I thought it might be Blossom Drop, but then realized I couldn't find a single dropped blossom anywhere around the base of the plants. The one thing I did find this morning was a small, green tomato (pea-sized) lying at the base of one of my cherry tomatoes.

FYI, I fertilized when I planted the seedlings back in March, then once more three weeks ago.

Do I have a pest? If so, what? And what can I do about it?