Plot dilemmas and a villain

On December 13, 2013, this came into the website from Alyssa: I reached a point in my book where I needed an explanation for something, but I couldn't think of one, so I just put something down so I could keep going. I don't really like the explanation, but it was the best thing I could come up with. Do you have any advice for moments like that?

Also, I feel like there are large parts of my book where I am just making things up as I go along. Is this normal for you, or do you have a general id...