Most of my tomato plants are looking good this year. However, as of a week and a half ago one plant in the center started looking wilty. Since then, it has completely self-destructed. Leaves started getting yellow spotting which quickly turned to brownish black. I pulled it out of the ground this evening as I noticed some yellow and brownish speckling on some leaves of an adjacent plant. I immediately noticed bumps all over the stem of the pulled plant in addition to the leaf damage and discoloration. There was also one small insect on it which can be seen next to the stem bumps.

The plants look otherwise very sturdy and healthy, at about 3 feet tall with numerous blooms but no fruit setting. Any help identifying the problem is greatly appreciated! If it is a disease vector spreading this, I'd like to get on top of it before the other eight plants die.