This is something that some birds will do, but he should be fine by now. Since he is eating some, then he is probably fine. If he is still acting the same now, then you should let the Vet know. Nail trims can be stressful, plus they do have a vein and nerves in the toes and toenail, so he may be experiencing some pain. It sounds like the grinding tool was scary for him, and the nails may have been ground too short. Some Vets do this because it is expensive for the client and they want the trim to last longer. Let the Vet know that the bird did not handle it well, and that next time you prefer the regular clippers and not cut the nails as short. Short nails will really affect the bird’s balance, so he is also feeling insecure from the short cut.
Thank you for asking Lafeber,