I just re-read this part of your post: "The first time I had this issue, I was taking a very strong laxative, Senna. Then, I drank way too much one night and had this issue...The most recent one, I was very sick with the flu, and last night it happened after I drank a lot of wine and ate ice cream( which I totally forgot was bad for me)."
I just have a few questions...I always do, forgive me.
Why did you take Senna? Are you regularly constipated or diarrhea-prone? How many times did you have diarrhea during that first episode? When you say you "drank way too much" during the second episode, how much alcohol are you talking about, ounces-wise? Was it more than four drinks in an evening? When you say you had "the flu," was this a stomach bug or an upper respiratory bug? And again, when you say you drank a lot of wine, how much is a lot?
I ask all these questions because it seems like every time you've had one of these "blackout" episodes, your body has been under stress (i.e., excessive alcohol intake, laxative use, flu, etc.). That's the most likely issue. If this were happening every other day, that'd be one thing...but once every two years is more than likely due to these various states of physical distress you've been in.
If I were you, I'd keep away from the alcohol, ice cream, and laxatives from now on. Sounds like it's a scary experience, but one you can learn from!