Baby fell and hit his head. he seems fine and acts normal. but he now has an area on his head that seems softer than normal. as if there is fluid. fall happened 3 days ago and he was assessed by a doctor almost immediately after fall?

Observe if okay: The swelling is most likely due to inflammation and some bleeding that is most likely going to go down by itself but slowly. As long as the baby is doing well and acting normal, there is no need to worry. If any change, like less active or irritable, recheck with your doctor. The swelling would go down slowly over period of days to weeks.