How to make baby drink water ?

Hello mumas

My baby is badly constipated now for second time after introducing solids. First time too it was hard journey to get the poop out visits to Gp lactulose juice water and what not

Now baby is constipated again and same thing poor baby stains but poop is too hard to come out GP says give lots of water but baby wont drink it

Any tips for making baby drink water ?

Any tips for getting stool soft so it comes out.. :(