Gave constipated 15 month old 1\4 pedia lax tablet....now her stool is yellow seedy and her bum is red and raw. is this normal? remedies for rash?

Common problem: Sounds like you fixed the constipation problem. Good job. Now you have the residual rash. I'd use, at baseline, a very good barrier cream such as 40% zinc oxide. Give her a little bath in tepid water twice daily with 3 tablespoons of baking soda. This will neutralize any fungal skin irritation. About 2-3 times daily use clotrimazole cream, OTC from drugstore. Be diligent and you can fix it!