Everyone's symptoms are different when they "get glutened" i.e., accidentally ingest gluten. However, many people's symptoms follow a predictable pattern... a pattern that clues them in that they've eaten something problematic (I describe my own personal pattern of symptoms below).
Although some people can't tell if they've eaten a gluten-containing food, the majority of people seem to get a reprise of celiac disease symptoms. However, they might not get the same symptoms they had before they were diagnosed.
That means you might see constipation now, even though your main digestive symptom was diarrhea prior to diagnosis. And there's evidence that some people suffer from reflux during a glutening, even if they didn't have that symptom before.
It's pretty normal to experience brain fog when you've been glutened, as well, and many people report recurrent bouts with gluten-caused depression that seem to clear up as soon as other symptoms clear up.
Although it's not common, I've heard of people vomiting due to accidentally ingesting gluten especially if they've ingested large amounts of it (as in, a slice of pizza or a doughnut).
My Glutening Symptoms Progress in a Pattern
Some people can tell immediately if they've been glutened.
Personally, I almost always can tell if I'm starting a major glutening I get unnaturally thirsty within a half-hour of exposure and my lips feel dry, and within another few minutes I start experiencing bad reflux. Fatigue hits within a couple of hours and I have trouble staying awake for the next several hours, but then that night, I suffer from insomnia. If I can sleep at all, I have nightmares.
The next day, I usually have cramps and diarrhea, plus major fatigue and brain fog. I also experience blurry vision, and can have some trouble focusing my eyes. By the third day, I usually feel better (unless the gluten exposure triggered a migraine), but I tend to suffer from constipation and joint pain for another day or two as my system recovers from the gluten exposure.
I used to get dermatitis herpetiformis almost exactly 22 hours after I'd been glutened (very helpful in pinpointing what got me). However, these days I'm healed enough that my itchy rash doesn't appear until about two days later, and sometimes it's only a minor itch and a few bumps.
It's more difficult to identify when I've been exposed to extremely small amounts of gluten, since I don't always get all my usual symptoms -- just some of them. However, the symptoms that do appear generally come in the usual order. I explain more about this in my article Symptoms: Major Gluten Exposure Versus Trace Gluten Exposure.
Still, all in all, a glutening (small or large) is an extremely unpleasant experience. When people ask me to describe my reaction to gluten, I characterize it as a "full-body flu"... and it's no wonder that so many of us work so hard to avoid gluten in our diets.