What you you mean by you get in a Christmassy mood when you get sick? Do you get the urge to listen to Christmas music, watch Christmas movies, or decorate? Do you get cravings for like eggnog and gingerbread?
Also, i’m sorry for you getting sick. That is a real bah humbug thing and I understand if it makes you a grouchy Grinch. Being sick sucks, almost as much as when the other reindeer wouldn’t let poor Rudolph join in their reindeer games or when grandma got run over by a reindeer. :/