Five short lines, and the poem works more like a jolt than a story. It says that "the image" speeds up, and what it speeds up is "an itinerant stomach ache / of distrusion." Itinerant means wandering, so the discomfort doesn't settle in one place. It travels, the way a vague unease can drift through you without a clear cause.
"Distrusion" isn't a standard English word. It looks like a blend of "distrust" and "intrusion," or perhaps "distrust" and "diffusion," and that fits the feeling: suspicion that creeps in uninvited. I'm reading that from the word itself, since the poem doesn't explain it.
The speaker doesn't say "I feel" anything, yet the mood is clear: queasy, restless, wary. Images, the poem hints, don't just sit there to be looked at. They rush, and they can leave a physical sense of mistrust behind. The title, "Thesis 17," suggests a claim being put forward, but the claim is delivered as a strange, bodily sensation rather than an argument.