I'm sorry that your question wasn't answered in a timely manner. Thank you for rescuing this budgie. You're necessarily constrained to confining it in a quiet, unlikely to be disturbed, and dimly lit area heated to 29.4C by means of a heating pad set on its lowest setting and placed around its enclosure. We don't treat head trauma in birds with drugs although we might prescribe a nonsteroidal antiinflammatory drug (NSAID) such as meloxicam if significant trauma is evident upon exam. Food and water should be readily available and should consist of more than seed. Ideally, a balanced pelleted diet such as can be found here: www.harrisonsbirdfoods.com or here: www.lafeber.com/pet-birds should be fed as well as hard boiled egg yolk, pancakes and cornbread, the tops of fresh greens, dairy products such as yogurt and cheese, fresh fruits such as apples, pears, melon, kiwi, and berries, vegetables such as broccoli, carrots, beets, asparagus, cabbage, sweet potato, and squash, and even tiny pieces of meat.
If you're going to keep this budgie it would be prudent to have an avian vet give it a thorough physical exam particularly if you have other birds at home. If that's the case, it's best to quarantine this bird away from your others for a month to see if any symptoms of infectious disease arise. Please respond with further questions or concerns if you wish.