Hi Mango:
Would you please verify that your baby Squirrel is back to her "regular self" and is active, interactive, paying, eating, pooping and peeing just like usual and that you do not notice anything different from how she was before the aspiration incident occurred. If so, that would IMO be justification for withholding the antibiotics and to continue to monitor her status another 48 hours and then if all is well, just retain the antibiotics tablet(s) (if not yet mixed but IF the antibiotic tablet has already been mixed, the mixture should be kept in the refrigerator and if not needed in the next few days it should be disposed of).
Did you mention that you had antibiotics on hand and that your were concerned about whether or not your Squirrel should be given antibiotics? If so, it seems as if the Vet was not in favor of utilizing antibiotics. Please verify this and also verify that the Veterinarian did not actually see your Squirrel and all this was accomplished at a distance.
I do not want to appear to be getting between you and your Veterinarian but Levocetirizine is an antihistamine is an antihistamine and its usual utilization is for an allergic mediated reaction. From what you have described this does not seem to be the case with your Squirrel. Did the Vet state his rationale for recommending this.
I will be at work and unable to regularly access TSB but I will check-in as I am able. Others are also here for you and your Squirrel!
Regards,
SamtheSquirrel