@deathlypoetic YES! I am having this same issue! I am trying to find the location on the map; where this mystery took place in hopes of finding an antidote or some other help to the madness. I have found that if I return to Raventhorpe and speak to either the Blacksmith or the Fish Hut Boy, the issue goes away until I die and respawn. Then the issue returns.
I have also noticed that while in Asgard...this is NOT an issue. So I am thinking this is an issue that only occurs in Eivor's "real world" which leaves me to believe there is an antidote or something that must be achieved in order to make the "poisoned state" disappear. Do you or anyone else know the location of this mystery or event so I can return and search? Or is this just a bug I have to live with?