Either way your bird is in trouble.
Undigested seeds - there is a raging digestive infection. Only a vet can prescribe medication strong enough to work.
A budgie "vomiting" seed is a good sign of trich - Trichomoniasis. This is a once celled organism that irroates the throat resulting in a heavy slime build up. The bird slings it's head to clear the throat. Seed caught in the slime flings out along with lots of slime. This coats the bird's head/face as well as the cage bars, etc. Left untreated the organism moves further and further into the digestive track while the irritated throat gets more painful so the bird can no longer swallow.
Waiting too long to treat the condition the bird gets over the tric, but is never an overly robust bird.
Don't seek treatment at all and the bird literary starves to death while frantically pulverizing the feed in the feed dish, but never swallowing a bite.
English exhibitors treat their entire flock across the board once a year. The medication we are now using is
Ronidazole in powdered form. A teaspoon desolves easily in a gallon of water. This is being highly recommended by vets who also participate in the exhibition of budgies.
You can purchase it at Foy's Pigeon Supply http://www.foyspigeonsupplies.com/ click on Product Catalog then click on canker products










