Baby's been having terrible constipation for the last three days and i…

Baby's been having terrible constipation for the last three days and it's hard for him to pass gas. What can I do to help? His stool is thick like that of an adult. He drinks water poorly and I force him to drink about 60 ml per day on average. He eats 125 ml every 3 hours. I give him biogas, beans, and nettle water.