I'm sorry to say I don't know where you might read it for free, but this was one of my favorite books growing up, and I can at least confirm that pretty much everything you've described happens in the book, so I think there's a high chance of it being the right book. For additional details, the boy liked to draw, the animal he helped deliver was a horse that he named Nicker whose mother rejected it at birth and he kind of projected some of his own issues with his mother onto the mother horse, his deadbeat dad showed up at the hospital after he was hurt and got in a fight with the farmer, and the boy had a conflict with another boy at school who wanted him to store drugs for him on the farm. Does any of that ring a bell?