So, a baby american robin fell from the nest and it's mother won't except it back, it hatched, like, yesterday and I think it's internally bleeding. I've read up and have been feeding Temmie mushed up worms and crushed dog food mixed with water.
If the baby is visibly injured, please take it to a wildlife rehab near you. They will know how to care for it so that it can be released.
Are you sure that the parent won't accept it back? Do you know where the nest is and have you tried putting the baby back in the nest? Bird parents will accept their young back even with human contact- that's a myth that they will reject the baby if it smells like humans.
If you know exactly the nest it fell from (shouldn't be too hard to find), it should be placed back into the nest for the parents to care for as nature intended. A baby that young is really hard to raise
properly. If you can't get the baby into its nest, call a local rehab person for their expertise. The parents will definitely take the kid back however.