Aiyoo this constipation thing memang stress jugak kan, I feel you! A few of my mum friends faced the same issue with their toddlers, and most of us found that increasing water intake and making sure dia makan enough fibre (like pureed fruits, oats, even sweet potato) helped more than supplements je, try konsisten dulu with diet before adding anything else. But honestly since dah tukar susu berkali-kali and doc dah check, better ask the paediatrician specifically about safe supplements for toddlers (some probiotics macam Lactobacillus actually help with this), sebab nak make sure it won't interfere with anything lain.