Prayers for my little one

I'm sorry for your bird's condition, Shruti. Budgies will usually flap wings very fast multiple times a day to get some exercise on a perch. But as you say she's vibrating and having seizures, that's not normal. You mentioned about itchiness....did your vet check for mites?
As aluz has suggested, if her condition worsens even a bit, get her checked immediately by an avian vet.
Hope Nike makes a speedy recovery.

It's good that she's able to crack open the seeds and also that she doesn't have a mite issue. Sorry, I don't know anything about de-worming medicines causing a lack of appetite.
Your vet will be able to enlighten you on the issue. Perhaps your vet will diagnose the real cause of her problem and prescribe her appropriate medications. From the pic you posted in the beginning, Nike looks fine....she's very cute.
Try feeding her electrolytes and pedialyte to keep her strength up and hydrated.
Good luck with the vet visit.

I'm very glad to know about the latest developments with Nike which are very encouraging. Guess she too doesn't want you to be sad and is trying to display normal signs. I hope she continues on the path to recovery.
How was your vet visit? Any news about it?