I can't account for the hangover part and everyone's usual and unusual symptoms, but I have a theory about the anxiety.
I do also get jittery and anxious etc after I've drank, on the next morning. I never thought about it until now, but it would sort of make sense, doesn't it?
Anxiety is in it's essence being completely uneasy about something. If you get comfortable, you are less anxious. You can get anxious around a lot of people you don't know, and then be okay around your friends or people you really trust, or on your own...
Hangovers are a reaction of your body to the alcohol, one you have not much control over, and which are very uncomfortable. Your body needs to recover. You have pushed it down with alcohol, but now it's back. So you feel out of control, uneasy- anxious. And once you are anxious, and too hungover to distract yourself, all your other anxieties can kick in.
I don't know, may be it's a stupid theory, it's just how I explain this for myself.