I think you acted wisely getting him to the vet and getting fluids into him and treating. Even minor and hopefully as all things point to this , get rapidly out of hand with dehydration and not keeping food down . Now he can feel better . And I agree feeling better is likely haveing him ask for food .
For myself, when treating my flock , I try and do the least restraint possible. I try very hard ( because I also feel free sbd worry, to display calmness . I try and create a treatment routine, I use the same spot , I use my ( pink for protection ) treatment towel for them to stand on, of I am able to I out the meds in a little made up baby bird formula in the syringe and letting their head be fre let them take it that way . Then I try to spend a few moments to calm and sweet talk and try and end on a good note . For those who would bite the ficken out of me I a talking Ta-dah and Phoebe. They will most often take the syringe through the cage bars or in food. When I have to ,they stand on the pink towel , and I use a pink hand towel on my hand that will restrain them with gentle pressure on their back with a finger st each shoulder wing point . So my hand is protected but they aren't wrapped,my other hand can give the meds with syringe and be out of bite range . With my budgies I did have to do bird burritos. And all of them fir nail trims I do have to do bird burritos. When I finished I set them on perch strp back and poor sweet bird thrm and offer treats
You will find your way , with what works for you . I myself wouldn't do scary bandana and such , but that is me . What's important is what you find works for you .
But after treating a whole flock of sick birds fir a very long time , I found energy, intent and a calm routine that they knew what was going to happen, even if they didn't like it went a long way , and the importance of ending on a good note .
I sure hope tomorrow you will be sharing your happiness with how much he has improved.
