I am sorry to hear you are worried about your poodle. This does sound strange, to stop eating and drinking after just being knocked over. My name is Rebecca. I am a veterinarian and will do my best to help.
Do you happen to have a copy of the blood tests I could look at?
What was the antibiotic, and the anti inflammatory?
Two things come to mind: he may have injured his neck or spinal cord in the accident. Were any Xrays taken? I might try some pain medication different from the anti inflammatory that was given earlie.
The other thing, just because he is a standard Poodle, is checking for Addison's disease. This is a condition where the adrenal glands are underactive, and the symptoms can be very subtle. A stressful event can make a dog with Addison's seem suddenly much worse.
On blood tests, classic Addison's shows low sodium and high potassium but there is "atypical Addisons" where these numbers are normal. An "ACTH stim test" is needed to check for Addison's.
Please let me know how he is doing and what other questions I can answer.