Because hangovers hurt!! They are the worst and you shake to try and get rid of it. OR it could be you drank too much the darkness before and your body is going thru withdraw. IF that's the skin...maybe try not drinking so much.
because they alcohol depressesthe nervous system and when its working its track out of they body's system it makes them do that.thats why your more "mellow" when drunk and jerky when your getting over it.