An intense version of love-sickness: To be madly in love, or heavily infatuated with girl by the name of Kristina or Krissy. Symptoms often include shallow breathing, lightness of head, inability to think of thing other than Kristina and/or romantic fantasies with this person. Cures are unheard of at this point in time.
"I love Kristina like nothing I have ever felt before... I can't stop thinking about her! There seems to be no cure for Krissinitis (but I don't really want there to be.)