Has anyone tried almond milk as a substitue for 3.25% milk for their toddler?

My 3.5 yr old is constantly constipated on 3.25% milk. Ive tried absolutely everything and so has his doctor. Our next try is to eliminate 3.25% milk and try almond milk. Has anyone had success with such a switch?

Yes, he has fruits and veggies and all the water in the world. We have tried it all. Im really hoping switching milk helps!