Expired Medicine

I was admitted on the 04 September 2022 in Melomed Bellville to give birth and when I was discharged I was given some medication for the newborn baby , I recently found out that one of the meds is expired and I have been administering my child for a month. The medicine expired 08/2022 and I went to the hospital hoping they would at least do some checks see if this did not harm my child . In the Pharmacy they called their manager/Pharmacist and all they did is to replace the medicine. My child was not even checked. The manager/ Pharmacist told me that nothing is wrong because there's grace period of 6 months after expiry date. I am wondering has the med saved its purpose if its expired. How do I know if this has not harm my child.