My 18 month old son has done something similar to this several times after something that was scary happened to him. (Major hospital/doctors visits)
It probably isn't comforting to know, but I would look at her recent sickness combined with the separation anxiety as a possible trigger. She got sick, wanted and needed comfort, and you provided that by having her sleep in your bed. Now she's having separation issues and is feeling a strong need for that kind of comfort again. If it isn't already a habit for her by now, it will be soon.
What has been working for my son so far has been a slow weaning process. Each week, I wait a little longer before going and getting him. Then I hold him for a while and then gently reaffirm that is bedtime and then put him back to bed. Not only do I wait a little longer before going and getting him each week, but I'm not holding him as long either.
The next step would be going in but not picking him up. Perhaps rubbing his back or helping him lay back down again. We haven't reached that point yet and we are going slowly so its not such a shock to him.
It also helped to buy him a lovie that he keeps with him. Grandma bought him a little stuffed monkey that he adores and he uses it to help self-comfort.
Good luck with whatever you choose to do. We let our first just cry it out and it was REALLY hard. It took her nearly a week before she would go back to sleep by herself.