Zanna,
I'm sorry to hear that you've been ill. I hope that you are feeling much better.
I would say wait only if you've had a high fever for a few days. In that case, I would just say to wash and condition your hair as usual for about two weeks and then get your relaxer. Especially when you've had a high fever, your hair can shed a bit, and then adding the chemicals is not a good mixture.
Cheers,
Jade