Hi Bren,
Welcome to our online family. You've already received so much good information that I don't have much to add, at this point. Your pattern of reactions pretty well matches mine. While most members here seem to have D every day, many times per day, when they are reacting, I would usually only have 6 to 8 episodes per day, for several days, and then I would have several good days - maybe a week, sometimes, followed by 2 or 3 days of nausea, and then several days of D, etc.
I'm not sure, but Jan and I may be the only ones here who are intolerant of oats. There are no medical tests available, by the way, to detect an intolerance to oats. That has to be determined by trial and error. IOW, Not everyone who is gluten-sensitive, is also avenin-sensitive, (avenin is the the prolamin protein in oats, that is the equivalent of gluten in wheat). You will note that both Jan and I have oats, (avenin), listed as an intolerance under our avatars. If you do a search of the archives, you can find topics describing a series of tests that I did a couple of years ago, to verify that I am sensitive to oats. If you should want to read about it, and can't find it, please let me know, and I'll look them up and post the links.
As Joan mentioned, your reaction to the Chinese food suggests that you might be sensitive to soy, (and possibly, gluten, of course).
The Honey Bunches of Oats cereal has several strikes against it. First, it contains hordein, the prolamin in barley, that is the equivalent of gluten in wheat, and second, it may contain gluten, since many sources of oats are cross-contaminated with wheat, and third, you may be intolerant of oats, though oat-intolerance is not nearly as common as gluten intolerance. Most mainstream commercial breakfast cereals contain some form of malt, or a malted product. If it turns out that you are gluten-sensitive, (and most of us are, of course), then you will have to avoid all products that contain any malted ingredients.
A much better cereal choice is Rice Chex. Last year, General Mills decided to do celiacs a favor, and they reformulated Rice Chex so that it is now gluten-free, and it still tastes just as good as it ever did. Of course, you can go to a health food store, (HF store), and find various types of gluten-free, (malt-free), cereals, such as corn flakes, quinoa, (pronounced "keen-wa"), buckwheat cereals, etc., but they will cost several times as much as the mainstream cereals, such as Rice Chex. Also, even in the HF stores, you have to read labels carefully, because they also sell many cereals that are not GF. Incidentally, FYI, buckwheat is not a member of the wheat family, so it's safe for all of us to eat. It's a paleo food, so no one is intolerant of it.
If you are interested in locating some good, gourmet quality GF, DF, (Dairy-Free), SF, (Soy-Free), recipes, Dee has hundreds of them posted here:
http://www.perskyfarms.com/phpBB2/viewforum.php?f=7
You mentioned that you thought at first, that you had the flu. Unlike you, mine came on slowly, I would get sick as as dog, and then I would be OK for two or three weeks. Believe it or not, for over a year, I really thought that I was having relapses of the flu, or food poisoning.

One day, though, the D started, and wouldn't stop, and that's when it dawned on me that something else was going on.
Sorry, didn't mean to write a book. As others have mentioned, whenever you have a question, or you are in doubt about anything, please don't hesitate to ask.
Again, welcome aboard,
Tex (Wayne)