How Soon Would An Infected Kitten Show Signs Of Flv?

We have had our kitten three months and she is showing signs of flv? She has been sneezing a lot, not eating and doesn’t want to get out of her carrier. I’m worried about her health because she acts like it hurts when we touch her head.

http://www.petmd.com/cat/conditions/respiratory_infections_upper_respiratory_tract_infectious%20diseases#flv