My Wife Gave Birth To My Baby Boy 2 Weeks

My wife gave birth to my baby boy 2 weeks ago. She is lactating and is suffering from loose motion (reaction of antibiotics, cefixime + azithromicin). after having breast milk, my boy is also suffusing from loose motion, frequency 2-3 times a day. doctor prescribed him darolac and vitazyme. my boy had darolac for 7 days but he hasn't cured fully. Please suggest me how long darolac can be taken??? what is the remedy for my boy???