CETIRIZINE - loose stools. Overdose?

Hello doctor, My baby is 8weeks (2months old)..he has skin rashes on hands, face. So pediatrician gave 5drops of ZYRTEC (CETIRIZINE) for 7days once in the evng. I didn't get drops in the pharmacy instead got ZYRTEC Syrup. By mistake I put 0.5ml considering each drop would be of 0.1ml. (One two drops extra also went) so almost 0.7ml. Yesterday only one day I have put. After overdose stopped putting it suddenly. I hope no problem to the baby as I have given overdose? As CETIRIZINE recommended after 6months but because of rashes doctor has given this. I hope no serious side effects will happen in one day. He slept a lot after medicine was given. He was drowsy almost 24hrs. But after that he is passing lot of gas with bright yellow loose stools after every feed. I am Sharing his stool pics. Plz chk is it worrisome. (Exclusively breastfed baby)