My son bumped his forehead the other day. he's got a swollen red soft bump it's been three days, should i worry that this could be a skull fracture?

Not likely: You say he bumped his forehead...Usually a skull fracture is more than a bump--like falling out of a shopping cart or high chair on to tile or tree or hitting a wall with some speed.....A skull fracture can have a boggy squishy area over it that appears a few days after the injury. It is not likely. If you are really concerned see your pediatrician.