My 1 year old cockatiel has been regurgitating/vomiting seed off/on for the past 4 days. It started on a weekend and the vet's office was not open. Monday, I took him to his avian vet who did a stool culture and a crop wash (both in house cytology) and IV hydration.  Tests did not show infection. They put him on two antibiotics just to be safe. He eats heartily (at times when he is not going through the vomiting) and is not puffed up or looking sick.

He has lost about 8 grams but is stable right now. His feces are fairly normal although a few days ago they were very dark green with few, if any, urates and he had been peeing clear and drinking excessively(that only lasted about 12 hours tops). The feces and pee situation have gone back to normal and he is no longer drinking or peeing copiously, but he continues to vomit seed from time to time.

His face is not covered in any gunk but he goes through phases where he flicks his head from side to side and seed will fly out. I see it on the bottom of the cage and outside the cage. Some of it is dried but some newer seeds (whole millet and what not) are still a little slimy from having been recently released. I cannot afford more expensive testing for him such as x-rays or detailed blood work. Do you have any suggestions??

He is still chewing on toys and playing with things and preening and eating fairly normally. I am at a loss. Thank you for any suggestions/advice. I am stuck between a rock and a hard place because my funds are very limited (husband lost his job).  Thank you.