There's a saying -- "because they can" -- ie they often lick their privates because they can. They can lick for other reasons, too. Yeast, allergies, etc... If she's irritated it's likely that she's getting a problem secondary to allergies and licking and should be seen by your veterinarian. A lot of the sneezing goes along with the same issues, but not all of it. Your veterinarian can help you minimize these symptoms or if you are looking for additional answers, see a veterinary dermatologist for even more options that may help her.
Would also like to add she has bad allergies, she sneezes a lot in the morning, and when she goes outside, discharging a lot of snot and she has reversed sneezing alot too.
Thanks