Suspect #1 - Otofuku (East 9th Street). A Japanese street vendor style hole in the wall that opens at 1:00 PM. Otofuku is something you can find on almost every street in Tokyo. It's as authentic as it gets. There's a tiny area at the window where two people are cooking everything. There's always a crowd outside Otofuku waiting for their food (since the only place to sit is the bench outside). It takes about 15 minutes per customer.
Their menu is simple and you can either get the okonomiyaki or takoyaki on its own or you can get it as a combo. The combo is a better deal since it's just $2 more. Everything on the menu is under $10.
This is where we got the green tea shaved ice pictured in an earlier post.
My other half ordered the okonomiyaki with corn and yakisoba combo. The yakisoba was delicious.
I ordered the okonomiyaki with shrimp and takoyaki combo. I'm not sure how long it takes before you digest your food and you begin to have symptoms for food poisoning, but I ate this meal at 1:30 PM and I didn't get sick until about 10:00 PM. 
Prime Suspect - Sakagura (East 43rd St.). Another place that feels like you've stepped out of New York and into Tokyo. It's a highly regarded sake bar and has been dubbed one of the best sake bars in the United States. It's located in the basement of an office building.
You walk in and it's dark, very crowded, and looks like a lot of the bars in Japan. The crowd is a mix of American and Japanese business men in suits that probably work in the area (or in the building) and casually dressed folks like us that just love sake. This photo captures one section of the sake bar. Notice all the sake bottles.
The amount of Sakagura's sake options are insane (something like 600+). We got a binder of sake options. Yes, a binder, categorized by type and then broken down by prefectures. We asked our waiter for recommendations and he kept recommending the expensive ones so we deemed him useless. So we did what we do best, which is simply zero in on the cheapest ones. You kind of have to do your homework before going to a place like Sakagura because unlike Sake Bar Decibel, which has fewer options and provides descriptions of their sake ("light and crisp" or "floral"), at Sakagura the descriptions are pretty sparse. Although we appreciated the sheer amount of choices at Sakagura (and if you're a wealthy person that loves sake, this place is your playground), we'd recommend Sake Bar Decibel, which is more relaxed, easier and fun.
This sake okyao don was possibly one of the dishes that make me sick, specifically the sweet salmon roe. I vomited a lot of the roe up so I definitely won't be able to eat that again.
The other possible (and most probable) culprit: sanma onigiri - three pieces of cooked rice balls with shiitake mushroom, pickled radish and mountain vegetables wrapped with a whole baked Pike Mackerel. One of the more interesting and different Japanese dishes I've tried. And maybe I paid the price. Seems the fish could have been old. 
I doubt this got me sick.
We're glad we didn't order dessert because as soon as we got in the cab, my stomach started to hurt badly. We had to tell the driver to drive as fast as he could to get us home quickly and we barely made it home in time. I've never experienced the kind of excruciating stomach pain I had that night and I rarely vomit when I'm sick but I couldn't stop vomiting. So it could have been the lunch but my metabolism works pretty fast so it was most likely dinner. I will never step foot into Sakagura again. I'm always careful about the food I eat since I'm paranoid about getting food poisoning and I guess being careful isn't enough when restaurants serve you bad food.
