Hello everyone! My son is 3 months old. A month and a half ago, he was…

Hello everyone! My son is 3 months old. A month and a half ago, he was in an infectious ward, they gave him antibiotics. Now he rarely poops, once every 5-7 days. The pediatrician said to give him Duphalac, but after it he cries very much, then Biobay, then another pediatrician says to give another medicine. Can you tell me who has encountered this? What should I give him?