I got that part. It was the pushing of the liquid in the duck. Maybe I had a weird syringe? Today we did another injection in the other breast and no problems at all. We'll see if it happens again I guess. Thank you for responding.You have to draw in air into the syringe before inserting into the vial of penicillin. and then push the air into the vial before drawing out the dose.
https://medlineplus.gov/ency/imagepages/19938.htm