Hi Bhargavi, Welcome to HealthcareMagic Forum.
I would like to know few things here, so that i can help you better:
1.) Has she sustained any Injury
to the neck?
2.) You haven't mentioned where on the neck is the swelling exactly?
3.) Is she having Pain?
4.) What do the Blood Test
You should be taking her to a Surgeon and Orthopedist so that they can examine her and do necessary tests to rule out the exact cause.
It could be a,
2.) Enlarged Lymph Node
All these have to be ruled out.
I Wish her Good Health.