Anyone have trouble getting sick from bad veggies?

This is a recurring problem for me. It used to be that my digestive system would not want to receive things like avocados and mushrooms at least 50% of the time that I would consume them... at the time I couldn't tell if I was just picking bad produce or if I had sensitivities to those things. I typically wouldn't vomit, but I would feel like I was on the verge of vomiting. This kind of thing happens once every month or two for me, and I can usually tell about 30 minutes after eating that my digestive system does not like what I just gave it, and it starts "shutting down." My stomach will get a little bloat, accompanied by foul gas eventually, or even like the episode that happened for me 2 months ago, weird burping. I'm not one to burp, so I know something's up when that happens. All I will be able to do is curl up in bed with the lights off and wait for my stomach to settle back down. It usually passes in an hour or two, but I can't do anything during that hour... not even sleep. 
Tonight, however, I threw up several times. I haven't thrown up in 5 years! For dinner I had a 2 champagne mangoes, large banana smoothie with cherry juice, followed by a romaine salad with mushrooms, small tomato, parsley, and some non-fat hummus from Whole Foods (not raw).  My gut tells me that it was something in the salad that pushed the "everybody out" button- I'm just left guessing which item.
Was the Romaine too aged and starting to rot and I couldn't tell?
Were the mushrooms a variety that I'm not used to?
Am I really able to eat mushrooms at all?
Was the parsley too potent and caused a detox reaction?
Was the parsley contaminated??
I don't think the tomato was bad?!

*sigh* I'm sorry. I'm just very tired of these episodes coming up, and very tired from them disrupting my sleep. It's not cool when it interferes with your job. It makes me feel like I'll never want to eat veggies again. Anyway, thanks for any pointers or words of encouragement. 
Who knows- maybe I'm actually sick this time and it has nothing to do with the food. o_0 Oh well. Perhaps I should have paid closer attention to my body's signals.
Peace.