Question about behaviour when giving budgies antibiotics

So i took my budgie to the vet and he has a respiratory infection and i was just wondering if this behaviour is an improvement or a need for worry (i have an anxiety disorder so that may be why this is worrying me so much) so before he got diagnosed he would puke up white bubbly things and we just dtarted giving him antibiotics last night and this morning and he hasnt puled since but he has been doing this thing where he bobs his neck where the front of his neck is still but the back of his neck goes up and down but he never starts doing the puking motion and im just curious if this is an improvement or if this in some ways is a bad sign? Also how long in your experiences does it normally take for a budgie to show a lot of improvement